Given:
\( \vec{a} = \hat{i} - \hat{k}, \quad \vec{b} = x\hat{i} + \hat{j} + (1 - x)\hat{k}, \quad \vec{c} = y\hat{i} + x\hat{j} + (1 + x - y)\hat{k} \)
Form the matrix:
\( M = \begin{bmatrix} 1 & x & y \\ 0 & 1 & x \\ -1 & 1 - x & 1 + x - y \end{bmatrix} \)
Find the determinant:
\( \det(M) = \begin{vmatrix} 1 & x & y \\ 0 & 1 & x \\ -1 & 1 - x & 1 + x - y \end{vmatrix} = 1 \)
Since the determinant is constant and non-zero, the vectors are linearly independent.
\( \boxed{\text{The matrix does not depend on } x \text{ or } y} \)
Given: \( \vec{a}, \vec{b} \) are unit vectors and
\( 2\vec{a} + \vec{b} = 3 \)
Take magnitude on both sides:
\( |2\vec{a} + \vec{b}| = 3 \Rightarrow |2\vec{a} + \vec{b}|^2 = 9 \)
Use identity:
\[ |2\vec{a} + \vec{b}|^2 = 4|\vec{a}|^2 + |\vec{b}|^2 + 4(\vec{a} \cdot \vec{b}) = 4 + 1 + 4(\vec{a} \cdot \vec{b}) = 5 + 4(\vec{a} \cdot \vec{b}) \]
Set equal to 9:
\[ 5 + 4(\vec{a} \cdot \vec{b}) = 9 \Rightarrow \vec{a} \cdot \vec{b} = 1 \Rightarrow \cos\theta = 1 \Rightarrow \theta = 0^\circ \]
Given:
\( \int f(x)\, dx = g(x) \)
Required: \( \int x^5 f(x^3)\, dx \)
Use substitution:
Let \( u = x^3 \Rightarrow du = 3x^2\, dx \Rightarrow dx = \frac{du}{3x^2} \)
Now rewrite the integral:
\[ \int x^5 f(x^3)\, dx = \int x^5 f(u) \cdot \frac{du}{3x^2} = \frac{1}{3} \int x^3 f(u)\, du \]
But \( x^3 = u \), so:
\[ \frac{1}{3} \int u f(u)\, du \]
Now integrate by parts or use the identity:
\[ \int u f(u)\, du = u g(u) - \int g(u)\, du \]
Final answer:
\[ \int x^5 f(x^3)\, dx = \frac{1}{3} \left[ x^3 g(x^3) - \int g(x^3) \cdot 3x^2\, dx \right] = x^3 g(x^3) - \int x^2 g(x^3)\, dx \]
\[ \boxed{ \int x^5 f(x^3)\, dx = x^3 g(x^3) - \int x^2 g(x^3)\, dx } \]
Given:
\[ \lim_{x \to 1} \frac{x^4 - 1}{x - 1} = \lim_{x \to k} \frac{x^3 - k^2}{x^2 - k^2} \]
LHS using derivative:
\[ \lim_{x \to 1} \frac{x^4 - 1}{x - 1} = \left.\frac{d}{dx}(x^4)\right|_{x=1} = 4x^3|_{x=1} = 4 \]
RHS using DL logic:
\[ \lim_{x \to k} \frac{x^3 - k^2}{x^2 - k^2} \approx \frac{3k^2(x - k)}{2k(x - k)} = \frac{3k}{2} \]
Equating both sides:
\[ \frac{3k}{2} = 4 \Rightarrow k = \frac{8}{3} \]
\[ \boxed{k = \frac{8}{3}} \]
Given:
We are to find:
Probability that no black ball is selected when 3 balls are drawn at random.
Step 1: Total number of ways to choose any 3 balls from 12:
\[ \text{Total ways} = \binom{12}{3} = 220 \]
Step 2: Ways to choose 3 balls such that no black ball is chosen:
Only yellow and green balls are allowed ⇒ Total = 5 (yellow) + 3 (green) = 8
\[
\text{Favorable ways} = \binom{8}{3} = 56
\]
Step 3: Probability
\[ P(\text{no black ball}) = \frac{\text{Favorable outcomes}}{\text{Total outcomes}} = \frac{56}{220} = \frac{14}{55} \]
\[ \boxed{\text{Probability} = \frac{14}{55}} \]
Given:
\( e^x \sin x = 1 \) has two real roots → say \( x_1 \) and \( x_2 \)
Apply Rolle’s Theorem:
Since \( f(x) = e^x \sin x \) is continuous and differentiable, and \( f(x_1) = f(x_2) \), ⇒ There exists \( c \in (x_1, x_2) \) such that \( f'(c) = 0 \)
Compute:
\[ f'(x) = e^x(\sin x + \cos x) = 0 \Rightarrow \tan x = -1 \] At this point, \[ e^x \cos x = -1 \]
\[ \boxed{\text{At least one root}} \]
Step 1: Define a helper polynomial:
\[ g(x) = f(x) - (x + 1) \]
Given: \( f(1) = 2, f(2) = 3, f(3) = 4, f(4) = 5 \Rightarrow g(1) = g(2) = g(3) = g(4) = 0 \)
So, \[ g(x) = A(x - 1)(x - 2)(x - 3)(x - 4) \quad \Rightarrow \quad f(x) = A(x - 1)(x - 2)(x - 3)(x - 4) + (x + 1) \]
Step 2: Use \( f(0) = 25 \) to find A:
\[ f(0) = A(-1)(-2)(-3)(-4) + (0 + 1) = 24A + 1 = 25 \Rightarrow A = 1 \]
Step 3: Compute \( f(5) \):
\[ f(5) = (5 - 1)(5 - 2)(5 - 3)(5 - 4) + (5 + 1) = 4 \cdot 3 \cdot 2 \cdot 1 + 6 = 24 + 6 = \boxed{30} \]
✅ Final Answer: \( \boxed{f(5) = 30} \)
Step 1: Let’s define the function:
\[ f(x) = (x - 1)^2 (x + 1)^3 \]
Step 2: Take derivative to find critical points
Use product rule:
Let \( u = (x - 1)^2 \), \( v = (x + 1)^3 \)
\[
f'(x) = u'v + uv' = 2(x - 1)(x + 1)^3 + (x - 1)^2 \cdot 3(x + 1)^2
\]
\[
f'(x) = (x - 1)(x + 1)^2 [2(x + 1) + 3(x - 1)]
\]
\[
f'(x) = (x - 1)(x + 1)^2 (5x - 1)
\]
Step 3: Find critical points
Set \( f'(x) = 0 \): \[ (x - 1)(x + 1)^2 (5x - 1) = 0 \Rightarrow x = 1,\ -1,\ \frac{1}{5} \]
Step 4: Evaluate \( f(x) \) at these points
\[ f\left(\frac{1}{5}\right) = \frac{16}{25} \cdot \frac{216}{125} = \frac{3456}{3125} \]
Step 5: Compare with given form:
It is given that maximum value is \( \frac{3456}{3125} = 2^p \cdot 3^q / 3125 \)
Factor 3456: \[ 3456 = 2^7 \cdot 3^3 \Rightarrow \text{So } p = 7, \quad q = 3 \]
✅ Final Answer: \( \boxed{(p, q) = (7,\ 3)} \)
Given Expression:
\[ (1 + x)^{1000} + 2x(1 + x)^{999} + 3x^2(1 + x)^{998} + \cdots + 1001x^{1000} \]
This follows a known identity that simplifies the full expression to:
\[ f(x) = (1 + x)^{1002} \]
Now: The coefficient of \( x^{50} \) in \( f(x) \) is:
\[ \boxed{\binom{1002}{50}} \]
✅ Final Answer: \( \boxed{\binom{1002}{50}} \)
Given:
\[ x_k = \cos\left(\frac{2\pi k}{n}\right) + i \sin\left(\frac{2\pi k}{n}\right) = e^{2\pi i k/n} \]
Required: Find: \[ \sum_{k=1}^{n} x_k \]
This is the sum of all \( n^\text{th} \) roots of unity (from \( k = 1 \) to \( n \)).
We know: \[ \sum_{k=0}^{n-1} e^{2\pi i k/n} = 0 \] So shifting index from \( k = 1 \) to \( n \) just cycles the same roots: \[ \sum_{k=1}^{n} e^{2\pi i k/n} = 0 \]
✅ Final Answer: \( \boxed{0} \)
Step 1: \( \cos x \) is differentiable everywhere, but \( |\cos x| \) is not differentiable where \( \cos x = 0 \).
Step 2: In the interval \( [-\pi, \pi] \), we have:
\[ \cos x = 0 \Rightarrow x = -\frac{\pi}{2},\ \frac{\pi}{2} \]
So \( f(x) = |\cos x| + 3 \) is not differentiable at these two points due to sharp turns.
✅ Final Answer: \( \boxed{2 \text{ points}} \)
Given: Point on parabola \( y^2 = 4a x \) is at distance \( 5a \) from focus \( (a, 0) \).
Distance Equation:
\[ (x - a)^2 + y^2 = 25a^2 \Rightarrow (x - a)^2 + 4a x = 25a^2 \Rightarrow x^2 + 2a x - 24a^2 = 0 \]
Solving gives: \( x = 4a \), \( y = 4a \)
✅ Final Answer: \( \boxed{(4a,\ 4a)} \)
Line: \( x + y - 1 = 0 \)
Point 1: (3, 2) → Lies on the side where value is positive:
\[
f(3, 2) = 3 + 2 - 1 = 4 > 0
\]
Point 2: \( (\cos\theta, \sin\theta) \) lies on same side if: \[ \cos\theta + \sin\theta > 1 \] Using identity: \[ \cos\theta + \sin\theta = \sqrt{2} \sin\left(\theta + \frac{\pi}{4}\right) \Rightarrow \sin\left(\theta + \frac{\pi}{4}\right) > \frac{1}{\sqrt{2}} \] So: \[ \theta \in \left(0,\ \frac{\pi}{2}\right) \]
✅ Final Answer: \( \boxed{\theta \in \left(0,\ \frac{\pi}{2}\right)} \)
Given: A vector of magnitude 5 makes equal angles with x, y, and z axes.
To Find: Sum of magnitudes of projections on each axis.
Let angle with each axis be \( \alpha \). Then, from direction cosine identity: \[ \cos^2\alpha + \cos^2\alpha + \cos^2\alpha = 1 \Rightarrow 3\cos^2\alpha = 1 \Rightarrow \cos\alpha = \frac{1}{\sqrt{3}} \]
Projection on each axis: \( 5 \cdot \frac{1}{\sqrt{3}} \)
Sum = \( 3 \cdot \frac{5}{\sqrt{3}} = \frac{15}{\sqrt{3}} = \boxed{5\sqrt{3}} \)
✅ Final Answer: \( \boxed{5\sqrt{3}} \)
Given: One ball is transferred from Bag I to Bag II, and then a ball is drawn from Bag II and is black.
Goal: Find the probability that the transferred ball was red, given that a black ball was drawn.
Using Bayes' theorem: \[ P(R|A) = \frac{P(R \cap A)}{P(A)} = \frac{\frac{3}{10} \cdot \frac{5}{10}}{\frac{3}{10} \cdot \frac{5}{10} + \frac{4}{10} \cdot \frac{6}{10} + \frac{3}{10} \cdot \frac{5}{10}} = \frac{15}{54} = \boxed{\frac{5}{18}} \]
✅ Final Answer: \( \boxed{\frac{5}{18}} \)
A force of 78 grams acts at the point (2,3,5). The direction ratios of the line of action being 2,2,1 . The magnitude of its moment about the line joining the origin to the point (12,3,4) is
Letters of the word QUEEN are E,E,N,Q,U
Words beginning with E (4!) = 24
Words beginning with N (4!/2!)=12
Words beginning with QE (3!) = 6
Words beginning with QN (3!/2!)= 3
Total words = 24+12+6+9=45
QUEEN is the next word and has rank 46th.
Not Available right now
For the two circles $x^2+y^2=16$ and $x^2+y^2-2y=0$, there is/are
A particle P starts from the point
Step 1: Use ellipse definition
$PF_1 = \sqrt{(0 - 4)^2 + (0 - 3)^2}
= \sqrt{25}
= 5$
$PF_2 = \sqrt{(0 - 12)^2 + (0 - 5)^2}
= \sqrt{169}
= 13$
Total distance = $5 + 13 = 18 \Rightarrow 2a = 18 \Rightarrow a = 9$
Step 2: Distance between the foci
$2c = \sqrt{(12 - 4)^2 + (5 - 3)^2} = \sqrt{64 + 4} = \sqrt{68} \Rightarrow c = \sqrt{17}$
Step 3: Find eccentricity
$e = \dfrac{c}{a} = \dfrac{\sqrt{17}}{9}$
✅ Final Answer: $\boxed{\dfrac{\sqrt{17}}{9}}$
If $\Delta=a^2-(b-c)^2$, where $\Delta$ is the are of the triangle ABC, then $tanA=$
Step 1: One-one (injective) function means no two elements map to the same output.
We choose 3 different elements from 5 and assign them to 3 inputs in order.
So, total one-one functions = $P(5,3) = 5 \times 4 \times 3 = 60$
✅ Final Answer: $\boxed{60}$
Vectors:
Step 1: Volume = $|\vec{a} \cdot (\vec{b} \times \vec{c})|$
First compute $\vec{b} \times \vec{c}$:
$ \vec{b} \times \vec{c} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 1 & -1 & 1 \\ 1 & 2 & -1 \end{vmatrix} = \hat{i}((-1)(-1) - (1)(2)) - \hat{j}((1)(-1) - (1)(1)) + \hat{k}((1)(2) - (-1)(1)) \\ = \hat{i}(1 - 2) - \hat{j}(-1 - 1) + \hat{k}(2 + 1) = -\hat{i} + 2\hat{j} + 3\hat{k} $
Step 2: Compute dot product with $\vec{a}$:
$\vec{a} \cdot (\vec{b} \times \vec{c}) = (m)(-1) + (1)(2) + (1)(3) = -m + 2 + 3 = -m + 5$
Step 3: Volume = $| -m + 5 | = 4$
So, $|-m + 5| = 4 \Rightarrow -m + 5 = \pm 4$
✅ Final Answer: $\boxed{m = 1 \text{ or } 9}$
Condition: Vectors are coplanar ⟹ Scalar triple product = 0
$\vec{a} \cdot (\vec{b} \times \vec{c}) = 0$
Step 1: Use determinant:
$ \vec{a} \cdot (\vec{b} \times \vec{c}) = \begin{vmatrix} \lambda^2 & 1 & 1 \\ 1 & \lambda^2 & 1 \\ 1 & 1 & \lambda^2 \end{vmatrix} $
Step 2: Expand the determinant:
$ = \lambda^2(\lambda^2 \cdot \lambda^2 - 1 \cdot 1) - 1(1 \cdot \lambda^2 - 1 \cdot 1) + 1(1 \cdot 1 - \lambda^2 \cdot 1) \\ = \lambda^2(\lambda^4 - 1) - (\lambda^2 - 1) + (1 - \lambda^2) $
Simplify:
$= \lambda^6 - \lambda^2 - \lambda^2 + 1 + 1 - \lambda^2 = \lambda^6 - 3\lambda^2 + 2$
Step 3: Set scalar triple product to 0:
$\lambda^6 - 3\lambda^2 + 2 = 0$
Step 4: Let $x = \lambda^2$, then:
$x^3 - 3x + 2 = 0$
Factor:
$x^3 - 3x + 2 = (x - 1)^2(x + 2)$
So, $\lambda^2 = 1$ (double root), or $\lambda^2 = -2$ (discard as it's not real)
Thus, real values of $\lambda$ are: $\lambda = \pm1$
✅ Final Answer: $\boxed{2}$ distinct real values
We are asked to count permutations of bottles such that exactly 5 bottles go into their own numbered boxes.
Step 1: Choose 5 positions to be fixed points (i.e., bottle number matches box number).
Number of ways = $\binom{9}{5}$
Step 2: Remaining 4 positions must be a derangement (no bottle goes into its matching box).
Let $D_4$ be the number of derangements of 4 items.
$D_4 = 9$
Step 3: Total ways = $\binom{9}{5} \times D_4 = 126 \times 9 = 1134$
✅ Final Answer: $\boxed{1134}$
Step 1: Find midpoint of PQ
Midpoint = \( \left( \dfrac{1 + k}{2}, \dfrac{4 + 3}{2} \right) = \left( \dfrac{1 + k}{2}, \dfrac{7}{2} \right) \)
Step 2: Find slope of PQ
Slope of PQ = \( \dfrac{3 - 4}{k - 1} = \dfrac{-1}{k - 1} \)
Step 3: Slope of perpendicular bisector = negative reciprocal = \( k - 1 \)
Step 4: Use point-slope form for perpendicular bisector:
\( y - \dfrac{7}{2} = (k - 1)\left(x - \dfrac{1 + k}{2}\right) \)
Step 5: Find y-intercept (put \( x = 0 \))
\( y = \dfrac{7}{2} + (k - 1)\left( -\dfrac{1 + k}{2} \right) \)
\( y = \dfrac{7}{2} - (k - 1)\left( \dfrac{1 + k}{2} \right) \)
Given: y-intercept = -4, so:
\( \dfrac{7}{2} - \dfrac{(k - 1)(k + 1)}{2} = -4 \)
Multiply both sides by 2:
\( 7 - (k^2 - 1) = -8 \Rightarrow 7 - k^2 + 1 = -8 \Rightarrow 8 - k^2 = -8 \)
\( \Rightarrow k^2 = 16 \Rightarrow k = \pm4 \)
✅ Final Answer: $\boxed{k = -4 \text{ or } 4}$
\[ x = 1 + 2^{1/6} + 4^{1/6} + 8^{1/6} + 16^{1/6} + 32^{1/6} \]
\[ x = 1 + a + a^2 + a^3 + a^4 + a^5 = 1 + \frac{a(a^5 - 1)}{a - 1} \]
\[ x = 1 + \frac{2 - a}{a - 1} = \frac{1}{a - 1} \Rightarrow 1 + \frac{1}{x} = a \Rightarrow \left(1 + \frac{1}{x} \right)^{24} = a^{24} \]
\[ a = 2^{1/6} \Rightarrow a^{24} = (2^{1/6})^{24} = 2^4 = \boxed{16} \]
✅ Final Answer: $\boxed{16}$
The exponent is an infinite geometric series: $$ 1 + |\sin x| + |\sin x|^2 + |\sin x|^3 + \cdots $$
This is a geometric series with first term \( a = 1 \), common ratio \( r = |\sin x| \in [0,1] \), so: $$ \text{Sum} = \frac{1}{1 - |\sin x|} $$
$$ 5^{\frac{1}{1 - |\sin x|}} = 25 = 5^2 $$
Equating exponents: $$ \frac{1}{1 - |\sin x|} = 2 \Rightarrow 1 - |\sin x| = \frac{1}{2} \Rightarrow |\sin x| = \frac{1}{2} $$
We want all \( x \in (-\pi, \pi) \) such that \( |\sin x| = \frac{1}{2} \)
So \( \sin x = \pm \frac{1}{2} \). Within \( (-\pi, \pi) \), the values of \( x \) satisfying this are:
✅ Final Answer: $\boxed{4}$ solutions
Goal: Find values of $\lambda$ and $\mu$ such that the system has infinitely many solutions
Step 1: Write Augmented Matrix
$ [A|B] = \begin{bmatrix} 1 & 2 & 2 & 5 \\ 1 & 2 & 3 & 6 \\ 1 & 2 & \lambda & \mu \end{bmatrix} $
Step 2: Row operations: Subtract $R_1$ from $R_2$ and $R_3$
$ \Rightarrow \begin{bmatrix} 1 & 2 & 2 & 5 \\ 0 & 0 & 1 & 1 \\ 0 & 0 & \lambda - 2 & \mu - 5 \end{bmatrix} $
Step 3: For infinitely many solutions, rank of coefficient matrix = rank of augmented matrix < number of variables (3)
This happens when the third row becomes all zeros:
$ \lambda - 2 = 0 \quad \text{and} \quad \mu - 5 = 0 $
$\Rightarrow \lambda = 2,\quad \mu = 5$
✅ Final Answer: $\boxed{\lambda = 2,\ \mu = 5}$
\[ W = |F| \cdot |D| \cdot \cos\theta \]
Given:
Step 1: Plug in the values:
\[ W = 40 \cdot 3 \cdot \cos(60^\circ) \]
Step 2: Use \( \cos(60^\circ) = \frac{1}{2} \)
\[ W = 40 \cdot 3 \cdot \frac{1}{2} = 60 \, \text{J} \]
✅ Final Answer: $\boxed{60 \, \text{J}}$
Married couple: 2 specific people among them
Total ways to choose 5 people from 9:
\[ \text{Total} = \binom{9}{5} = 126 \]
We fix the married couple (2 people), then choose 3 more from remaining 7:
\[ \binom{7}{3} = 35 \]
We remove both from the pool, then choose 5 from remaining 7:
\[ \binom{7}{5} = \binom{7}{2} = 21 \]
\[ \text{Favorable} = 35 + 21 = 56 \]
\[ \text{Required Probability} = \frac{56}{126} = \frac{28}{63} = \frac{4}{9} \]
✅ Final Answer: $\boxed{\dfrac{4}{9}}$
\[ \sin(4x) = \frac{1}{2}, \quad x \in (-9\pi,\ 3\pi) \]
Step 1: General solutions for \( \sin(θ) = \frac{1}{2} \)
\[ θ = \frac{\pi}{6} + 2n\pi \quad \text{or} \quad θ = \frac{5\pi}{6} + 2n\pi \]
Let \( θ = 4x \), so we get:
By checking all possible \( n \) values, we find:
✅ Final Answer: $\boxed{48}$
We want: Probability that exactly 2 recover out of 3.
\[ P(X = r) = \binom{n}{r} p^r (1 - p)^{n - r} \] where \( n = 3, r = 2, p = 0.6 \)
\[ P(X = 2) = \binom{3}{2} (0.6)^2 (0.4)^1 = 3 \times 0.36 \times 0.4 = 0.432 \]
✅ Final Answer: $\boxed{0.432}$
\[ \text{Evaluate } \tan\left(\frac{\pi}{4} + \theta\right) \cdot \tan\left(\frac{3\pi}{4} + \theta\right) \]
\[ \tan\left(A + B\right) = \frac{\tan A + \tan B}{1 - \tan A \tan B} \] But we don’t need expansion — use known angle values:
\[ \tan\left(\frac{\pi}{4} + \theta\right) = \frac{1 + \tan\theta}{1 - \tan\theta} \]
\[ \tan\left(\frac{3\pi}{4} + \theta\right) = \frac{-1 + \tan\theta}{1 + \tan\theta} \]
\[ \left(\frac{1 + \tan\theta}{1 - \tan\theta}\right) \cdot \left(\frac{-1 + \tan\theta}{1 + \tan\theta}\right) \]
Simplify:
\[ = \frac{(1 + \tan\theta)(-1 + \tan\theta)}{(1 - \tan\theta)(1 + \tan\theta)} = \frac{(\tan^2\theta - 1)}{1 - \tan^2\theta} = \boxed{-1} \]
\[ \boxed{-1} \]
\[ \sin x = \sin y \quad \text{and} \quad \cos x = \cos y \]
\[ \sin x = \sin y \Rightarrow x = y + 2n\pi \quad \text{or} \quad x = \pi - y + 2n\pi \]
\[ \cos x = \cos y \Rightarrow x = y + 2m\pi \quad \text{or} \quad x = -y + 2m\pi \]
For both \( \sin x = \sin y \) and \( \cos x = \cos y \) to be true, the only consistent solution is:
\[ x = y + 2n\pi \Rightarrow x - y = 2n\pi \]
\[ \boxed{x - y = 2n\pi \quad \text{for } n \in \mathbb{Z}} \]
What is the probability that they contradict each other while narrating an incident?
Total probability of contradiction: \[ P(\text{Contradiction}) = 0.2 + 0.3 = \boxed{0.5} \]
\[ \boxed{\frac{1}{2}} \]
\[ \boxed{ \vec{OP} = \left( \frac{-1}{\sqrt{2}},\ \frac{7}{\sqrt{2}} \right) } \]
Let the number be \( x \).
So, \( x + 5 \) is divisible by LCM of 9, 10, 15, 20
LCM = \( 2^2 \cdot 3^2 \cdot 5 = 180 \)
\( x + 5 = 180 \times 2 = 360 \Rightarrow x = 355 \)
Question: Find the value of:
$$ \sum_{r=1}^{n} \frac{nP_r}{r!} $$
Solution:
We know: \( nP_r = \frac{n!}{(n - r)!} \Rightarrow \frac{nP_r}{r!} = \frac{n!}{(n - r)! \cdot r!} = \binom{n}{r} \)
Therefore,
$$ \sum_{r=1}^{n} \frac{nP_r}{r!} = \sum_{r=1}^{n} \binom{n}{r} = 2^n - 1 $$
Final Answer: $$ \boxed{2^n - 1} $$
Given: Two events \( A \) and \( B \) defined on sample space \( \Omega \). We are to find the probability:
$$ P\left((A \cap B^c) \cup (A^c \cap B)\right) $$
Step 1: This is the probability of events that are in exactly one of A or B (but not both), i.e., symmetric difference of A and B:
$$ (A \cap B^c) \cup (A^c \cap B) = A \Delta B $$
Step 2: So, we use:
$$ P(A \Delta B) = P(A) + P(B) - 2P(A \cap B) $$
Final Answer:
$$ \boxed{P(A) + P(B) - 2P(A \cap B)} $$
Given: $$x^2 + 2y^2 = 3 \text{ and } x > y \text{ with } x, y \in \mathbb{Z}$$
Solutions to the equation are: $$\{(1,1), (1,-1), (-1,1), (-1,-1)\}$$
Among them, only \( (1, -1) \) satisfies \( x > y \).
Answer: $$\boxed{1}$$
Given:
$$f\left(\frac{1 - x}{1 + x}\right) = x + 2$$
To Find: \( f(1) \)
Let \( \frac{1 - x}{1 + x} = 1 \Rightarrow x = 0 \)
Then, \( f(1) = f\left(\frac{1 - 0}{1 + 0}\right) = 0 + 2 = 2 \)
Answer: $$\boxed{2}$$
What can we say about the median of the combined set \( A \cup B \)?
The combined median depends on the size and values of both sets.
Without that information, we only know that:
\[ \text{Combined Median} \in [2, 4] \]
So, the exact median cannot be determined with the given data.
Favorable outcomes (odd heads):
Total favorable = \( 8 + 56 + 56 + 8 = 128 \)
So, Probability = \( \frac{128}{256} = \boxed{\frac{1}{2}} \)
Given Function: $$f(x) = x^{2/3}(6 - x)^{1/3}$$
Correct Answer (False Statement): $$\boxed{\text{f is decreasing in } (6, \infty)}$$
Evaluate: $$\lim_{x \to 0} \frac{e^x - e^{-x} - 2x}{1 - \cos x}$$
Step 1: Apply L'Hôpital's Rule (since it's 0/0):
First derivative: $$\frac{e^x + e^{-x} - 2}{\sin x}$$
Still 0/0 → Apply L'Hôpital's Rule again: $$\frac{e^x - e^{-x}}{\cos x}$$
Now, $$\lim_{x \to 0} \frac{1 - 1}{1} = 0$$
Final Answer: $$\boxed{0}$$
If one Arithmetic Mean (AM) \( a \) and two Geometric Means \( p \) and \( q \) are inserted between any two positive numbers, find the value of: \[ p^3 + q^3 \]
\[
pq = \sqrt[3]{A^2B} \cdot \sqrt[3]{AB^2} = \sqrt[3]{A^3B^3} = AB
\]
\[
p^3 = A^2B, \quad q^3 = AB^2
\]
\[
p^3 + q^3 = A^2B + AB^2 = AB(A + B)
\]
\[ 2apq = 2 \cdot \frac{A + B}{2} \cdot AB = AB(A + B) \]
\( \boxed{p^3 + q^3 = 2apq} \)
Given the equation: \( Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 \)
Compute: \( \Delta = B^2 - 4AC \)
For the equation: \( 3x^2 + 10xy + 11y^2 + 14x + 12y + 5 = 0 \)
\( A = 3 \), \( B = 10 \), \( C = 11 \) →
\( \Delta = 10^2 - 4(3)(11) = 100 - 132 = -32 \)
Since \( \Delta < 0 \), it represents an ellipse.
Points: \( A = (1, \frac{1}{2}) \), \( B = (3, -\frac{1}{2}) \)
Line: \( 2x + 3y = k \)
For A: \( 2(1) + 3\left(\frac{1}{2}\right) = \frac{7}{2} \)
For B: \( 2(3) + 3\left(-\frac{1}{2}\right) = \frac{9}{2} \)
The correct statements are:
A crate is pulled 25 m along a dock with a force of 180 N at an angle of 45°.
\[ \text{Work} = F \cdot d \cdot \cos(\theta) \]
\[ W = 180 \times 25 \times \cos(45^\circ) = 180 \times 25 \times 0.70710678118 = 3181.98052\, \text{J} \]
\[ \boxed{3.181\times 10^3 \, \text{Joules}} \]
\[ \vec{A} = (2x + 1)\hat{i} + (x^2 - 6y)\hat{j} + (xy^2 + 3z)\hat{k} \]
\[ \nabla \cdot \vec{A} = 2 - 6 + 3 = -1 \neq 0 \]
Not solenoidal ❌
\[ \nabla \times \vec{A} = (2xy)\hat{i} - (y^2)\hat{j} + (2x)\hat{k} \neq \vec{0} \]
Not conservative ❌
\( \vec{A} \) is neither conservative nor solenoidal.
Given vector field:
\[ \vec{A} = (2x + 1)\hat{i} + (x^2 - 6y)\hat{j} + (xy^2 + 3z)\hat{k} \]
\[ \nabla \cdot \vec{A} = 2 - 6 + 3 = -1 \]
The divergence is negative at every point, so \( \vec{A} \) is a sink field.
Given: \( R = \{ (x, y) \in \mathbb{R}^2 \mid x^2 + y^2 < 4 \} \) in the first quadrant
Area of region \( R \) in first quadrant: \[ A = \frac{1}{4} \pi (2)^2 = \pi \]
Region where \( r > s \) (i.e., below line \( x = y \)) occupies half of that quarter-circle: \[ A_{\text{favorable}} = \frac{1}{2} \pi \]
Therefore, the required probability is:
\[ \text{Probability} = \frac{\frac{1}{2} \pi}{\pi} = \boxed{\frac{1}{2}} \]
Given:
\[ \text{Total line pairs: } \binom{10}{2} = 45 \]
\[ \text{Subtract parallel pairs: } \binom{5}{2} = 10 \Rightarrow 45 - 10 = 35 \]
\[ \text{Concurrent at one point: reduce } 10 \text{ pairs to 1 point} \Rightarrow 35 - 9 = \boxed{26} \]
The line \[ a^2x + ay + 1 = 0 \] is normal to the curve \[ xy = 1 \]. Find possible values of \( a \in \mathbb{R} \).
Rewrite: \[ y = -a x - \frac{1}{a} \] → slope = \( -a \)
\[ xy = 1 \Rightarrow \frac{dy}{dx} = -\frac{y}{x} \] Slope of normal = \( \frac{x}{y} \)
\[ -a = \frac{x}{y} \Rightarrow x = -a y \]
\[ xy = 1 \Rightarrow (-a y)(y) = 1 \Rightarrow y^2 = -\frac{1}{a} \]
For real \( y \), we need \( a < 0 \)
\[ \boxed{a < 0} \]
Given:
We use the inclusion-exclusion principle:
\[ |M \cup P \cup C| = |M| + |P| + |C| - |M \cap P| - |M \cap C| - |P \cap C| + |M \cap P \cap C| \]
Let \( x = |M \cap P \cap C| \). Then:
\[ 50 \geq 37 + 24 + 43 - 19 - 29 - 20 + x \Rightarrow 50 \geq 36 + x \Rightarrow x \leq 14 \]
Function:
\[ f(x) = \begin{cases} \dfrac{x}{e^{\pi x} - 1}, & x \neq 0 \\ \dfrac{1}{\pi}, & x = 0 \end{cases} \]
\[ \lim_{x \to 0} f(x) = \frac{1}{\pi} = f(0) \quad \Rightarrow \quad \text{Function is continuous at } x = 0 \]
\[ f'(0) = \lim_{h \to 0} \frac{f(h) - f(0)}{h} = -\frac{1}{2} \]
Given:
\[ f(x) = \cos\left([\pi^2]x\right) + \cos\left([-\pi^2]x\right) \]
Find: \[ f\left(\frac{\pi}{2}\right) \]
\[ \pi^2 \approx 9.8696 \Rightarrow [\pi^2] = 9,\quad [-\pi^2] = -10 \]
\[ f\left(\frac{\pi}{2}\right) = \cos\left(9 \cdot \frac{\pi}{2}\right) + \cos\left(-10 \cdot \frac{\pi}{2}\right) = \cos\left(\frac{9\pi}{2}\right) + \cos(-5\pi) \]
\[ \cos\left(\frac{9\pi}{2}\right) = 0,\quad \cos(-5\pi) = -1 \]
\[ \boxed{-1} \]
Total numbers divisible by 6 from 1 to 100: 16
\[ \binom{100}{3} = 161700, \quad \binom{16}{3} = 560 \]
Probability: \[ \frac{560}{161700} = \frac{4}{1155} \]
Given:
Use empirical formula:
\[ \text{Mode} = 3 \cdot \text{Median} - 2 \cdot \text{Mean} \]
\[ 9^x = 3 \cdot 3^x - 2 \Rightarrow (3^x)^2 = 3 \cdot 3^x - 2 \]
Let \( y = 3^x \), then:
\[ y^2 = 3y - 2 \Rightarrow y^2 - 3y + 2 = 0 \Rightarrow (y - 1)(y - 2) = 0 \]
So, \( y = 1 \text{ or } 2 \Rightarrow 9^x = y^2 = 1 \text{ or } 4 \)
\[ S = \frac{2}{3!} + \frac{4}{5!} + \frac{6}{7!} + \cdots = \sum_{n=1}^{\infty} \frac{2n}{(2n+1)!} \]
This is a known convergent series, and its sum is:
\[ \boxed{e^{-1}} \]
np = 4
npq = 2
q = 1/2, p = 1/2, n = 8
p(X = 1) = 8C1 (1/2)(1/2)7
Class Interval | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 |
Frequency | 180 | $f_1$ | 34 | 180 | 136 | $f_2$ | 50 |
Size of item | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
Frequency | 3 | 6 | 9 | 13 | 8 | 5 | 4 |
Total number of items in the distribution = Σ fi = 3 + 6 + 9 + 13 + 8 + 5 + 4 = 48.
The Mean (x̅) of the given set = \(\rm \dfrac{\sum f_i x_i}{\sum f_i}\).
⇒ x̅ = \(\rm \dfrac{6\times3+7\times6+8\times9+9\times13+10\times8+11\times5+12\times4}{48}=\dfrac{432}{48}\) = 9.
Let's calculate the variance using the formula: \(\rm \sigma^2 =\dfrac{\sum x_i^2}{n}-\bar x^2\).
\(\rm \dfrac{\sum {x_i}^2}{n}=\dfrac{6^2\times3+7^2\times6+8^2\times9+9^2\times13+10^2\times8+11^2\times5+12^2\times4}{48}=\dfrac{4012}{48}\) = 83.58.
∴ σ2 = 83.58 - 92 = 83.58 - 81 = 2.58.
And, Standard Deviation (σ) = \(\rm \sqrt{\sigma^2}=\sqrt{Variance}=\sqrt{2.58}\) ≈ 1.607.
Given: Perimeter = 6 × Arithmetic Mean of sin A, sin B, sin C
Using Law of Sines: \( \frac{a}{\sin A} = 2R \), and a = 1 ⇒ \( \sin A = \frac{1}{2R} \)
Assume \( A = 30^\circ \Rightarrow \sin A = \frac{1}{2} \Rightarrow 2R = 2 \)
⇒ b = 2 sin B, c = 2 sin C
Perimeter = \( 1 + b + c = 1 + 2 \sin B + 2 \sin C \)
Mean = \( \frac{\sin A + \sin B + \sin C}{3} \)
Check: \( 1 + 2\sin B + 2\sin C = 6 \cdot \frac{1/2 + \sin B + \sin C}{3} \) ✅
✅ Final Answer: 30°
Total Papers: 9
Condition for Success: Passes > Fails
So, candidate is unsuccessful when: Passes ≤ 4
Calculate ways:
\[ \text{Ways} = \sum_{x=0}^{4} \binom{9}{x} = \binom{9}{0} + \binom{9}{1} + \binom{9}{2} + \binom{9}{3} + \binom{9}{4} \]\[= 1 + 9 + 36 + 84 + 126 = \boxed{256}\]
✅ Final Answer: 256 ways
Original Mean: 40, Standard Deviation: 15
Two scores were misread: 25 → 52 and 35 → 53
Corrected Mean:
\( \mu' = \frac{3955}{100} = \boxed{39.55} \)
Corrected Standard Deviation:
\( \sigma' = \sqrt{\frac{178837}{100} - (39.55)^2} \approx \boxed{14.96} \)
✅ Final Answer: Mean = 39.55, Standard Deviation ≈ 14.96
Class interval | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 |
Frequency | 180 | $f_1$ | 34 | 180 | 136 | $f_2$ | 50 |
Given: Median = 42.6, Total Frequency = 685
Using Median Formula:
\( \text{Median} = L + \left( \frac{N/2 - F}{f} \right) \cdot h \)
Substituting values:
\( 42.6 = 40 + \left( \frac{128.5 - f_1}{180} \right) \cdot 10 \Rightarrow f_1 = \boxed{82} \)
Using total frequency:
\( 662 + f_2 = 685 \Rightarrow f_2 = \boxed{23} \)
✅ Final Answer: \( f_1 = 82,\quad f_2 = 23 \)
Given: \( f(x) = x^3 + 3x - 9 \)
The sum of infinite GP = max value of \( f(x) \) on [−2, 3]
The difference between first two terms = \( f'(0) \)
Step 1: \( f(x) \) is increasing ⇒ Max at \( x = 3 \)
\( f(3) = 27 \Rightarrow \frac{a}{1 - r} = 27 \)
Step 2: \( f'(x) = 3x^2 + 3 \Rightarrow f'(0) = 3 \)
⇒ \( a(1 - r) = 3 \)
Step 3: Solve:
\( a = 27(1 - r) \)
\( \Rightarrow 27(1 - r)^2 = 3 \Rightarrow (1 - r)^2 = \frac{1}{9} \Rightarrow r = \frac{2}{3} \)
✅ Final Answer: \( r = \frac{2}{3} \)
Given Equation: \( x^2 + 2x - 4y^2 + 8y - 7 = 0 \)
Step 1: Complete the square
⇒ \( (x + 1)^2 - 4(y - 1)^2 = 4 \)
Rewriting: \( \frac{(x + 1)^2}{4} - \frac{(y - 1)^2}{1} = 1 \)
This is a horizontal hyperbola with:
✅ Foci: \( (-1 \pm \sqrt{5},\ 1) \)
Given Parabola: \( y^2 = 4x \)
Condition: Chords pass through the vertex \( (0, 0) \)
Let the other end of the chord be \( (x_1, y_1) \), so the midpoint is:
\( M = \left( \frac{x_1}{2}, \frac{y_1}{2} \right) = (h, k) \)
Since the point lies on the parabola: \( y_1^2 = 4x_1 \)
⇒ \( (2k)^2 = 4(2h) \)
⇒ \( 4k^2 = 8h \)
⇒ \( \boxed{k^2 = 2h} \)
✅ Locus of midpoints: \( y^2 = 2x \)
Online Test Series, Information About Examination,
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Online Test Series, Information About Examination,
Syllabus, Notification
and More.