Calculus (Antiderivatives)
posted by Mishaka .
What is the antiderivative of the following expression?
3x(x^2 + 7)^3

hard way: expand the product:
3x^7 + 63x^5 + 441x^3 + 1029x
integral is
3/8 x^8 + 21/2 x^6 + 441/4 x^4 + 1029/2 x^2
easy way: let u = x^2+7
du = 2x dx
Integral of 3/2 u^3 du
is
3/8 u^4 = 3/8 (x^2+7)^4