Question

Find the derivative of y = (x2 +5)(3x+1).

Answer 1

Answer:

y = (x2 +5)(3x+1)

y = x2(3x+1)+5(3x+1)

y = 3x3+x2+15x+5

dy/dx = 9x2+2x+15

feel free to correct me if I'm wrong

Answer 2

y ' = 4 x ( x 2 + 5 )

Explanation:

Use the chain rule and the power rule:  

( u n) ' = n u n − 1 u '  y ' = 2 ( x 2 + 5 ) 1 ( 2 x )  y ' = 4 x ( x 2 + 5 )