Answer
Foci: $(±2,0)$ (No matter the value of $k$)
Work Step by Step
$4+k\gt k$. So, the major axis is vertical.
$\frac{x^2}{k}+\frac{y^2}{4+k}=1$
$a^2=4+k$
$b^2=k$
$c^2=a^2-b^2=4+k-k=4$
$c=2~~$
Foci: $(±c,0)=(±2,0)$ (No matter the value of $k$)
