integral (2x+3) (x^2+3x)^5

Misal :
u = x² + 3x
du/dx = 2x + 3
(2x + 3) dx = du

∫(x² + 3x)^5 . (2x + 3)dx
= ∫u^5 du
= 1/6 u^6 + c
= 1/6 (x² + 3x)^6 + c