Question

Will someone help me with problem 21?

Answer 1

Sin^(1/2) x cos x - sin^(5/2) cos x
= sin^(1/2) x cos x - sin(1/2)x sin^2 x cos x
factoring we get:
cos x sin^(1/2) x ( 1 - sin^2 x)
Now 1 - sin^2 x = cos^2 x so we have

cos x sin^(1/2) x * cos^2 x

= cos^3 x sqrt sin x