Answer
a) $\cos \pi x+C$
b) $-3 \cos x+C$
c) $\dfrac{-1}{\pi} \cos \pi x+\cos 3x+C$
Work Step by Step
a) The anti-derivative is:
$-\pi (\dfrac{-1}{\pi} \cos \pi x)=\cos \pi x+C$
b) The anti-derivative is:
$3( -\cos x)=-3 \cos x+C$
c) The anti-derivative is:
$\dfrac{-1}{\pi} \cos \pi x- 3(\dfrac{-1}{3} \cos 3 x) +C=\dfrac{-1}{\pi} \cos \pi x+\cos 3x+C$
