# Calculus - please check my work

posted by
**Henry**
.

differentiate each function

a) y = cos^3x

b) y = sin(x^3)

c) y = sin^2 xcos3x

my answers:

a) y' = 3cos^2 x(-sinx)

b) y' = cos(x^3)(3x^2)

c) for this one, i don't know which one is correct. i got 2 different answers but i think they may be the same.. im not sure, i did it twice and got 2 diff answers, please let me know which is right or if they are both wrong. first answer for c: y' = 2sinxcosxcos3x + 3cos2x(-sinx)sin^2x or 2nd answer for c: y' = 2sinxcosxcos3x + (-sin3x)(3)(sin^2x)

thank you