Question: Differentiate with respect to x

a. y=3sin^2(2x-4) - 2cos^2 (3x+1)

b. y=sin(x^2 + pi)

My teacher says for these questions, i need to use the product rule/chain rule/power rule/sum or difference rule/quotient rule etc. I know the derivative of y=sinx is y'= cosx and the derivative of y=cosx is y'=-sinx.

Please help in solving these.Thank you.