How do you integrate intx(4x+5)^3 using substitution?

1 Answer
Feb 7, 2017

=>1/80(4x + 5)^5 - 5/64(4x + 5)^4 + C

Explanation:

Let u = 4x + 5. Then du =4dx -> dx= (du)/4. This also means that x = (u - 5)/4.

=>int (u - 5)/4 u^3 (du)/4

=>1/16intu^4 - 5u^3du

=>1/16(1/5u^5 - 5/4u^4) + C

=>1/80u^5 - 5/64u^4 + C

=>1/80(4x + 5)^5 - 5/64(4x + 5)^4 + C

Hopefully this helps!