Question

I reallllllyyy need help, it's literally my last question and Im stuck on it.

Answer 1

We have
$h(x)=\cos (kx)*f(x)+\sin x$

We take the derivative of $h(x)$:
$h'(x)=\cos (kx)*f'(x)+k(-\sin (kx))*f(x)+\cos x$

Now we simply plug in 0:
$h'(0)=\cos (k*0)*f'(0)-k\sin (k*0)*f(0)+\cos 0$
$=\cos 0 *5-k\sin 0 *3+\cos 0$
$=5*1-3k*0+1$
$=5+1$
$=6$