For quadratic $ax^2+bx+c>0$ for all $x$:
$a>0$ → $k-2>0$ → $k>2$
Discriminant $<0$
$D=b^2-4ac=8^2-4(k-2)(k+4)$
Compute:
$D=64-4(k^2+2k-8)=64-4k^2-8k+32$
$D=96-4k^2-8k<0$
Divide by $-4$:
$k^2+2k-24>0$
$(k+?)(k+?)$ → roots $4$ and $-6$
So $k>4$ or $k<-6$
Combine with $k>2$ ⇒ $k>4$
Least integer = $5$