f 2x cos x  dx = f (x+2) sin x dx =

saya bantu 1 aja, yg pertama :
∫cos²(x)sin(x)dx 
Let u = cos(x) 
du = -sin(x)dx 

∫cos²(x)sin(x)dx 
= ∫-u²du 
= -u³/3 + c 
= -(1/3)cos³(x) + c

no 2 pake cara parsial (x+2)(sin x) (1)(cos x) + (0)(-sin x) - jadi integral (x+2)sin x dx =(x+2)cos x + sin x + c