hanya 1 soal beserta caranya saya kurang paham

Int (2x^2 + x)^2 (4x + 1) dx
Misal
u = 2x^2 + x
du/dx = 4x + 1
du/(4x + 1) = dx

Int (2x^2 + x)^2 (4x + 1) dx
= Int u^2 . (4x + 1) du/(4x + 1)
= Int u^2 du
= 1/3 u^3 + C
= 1/3 (2x^2 + x)^3 + C

^ = pangkat
Int = integral