(3A) integral x.sin2x dx (menggunakan intergral persial)

Integrate by Parts.

∫ u dv = uv - ∫ v du
u = x → du = dx
dv = sin 2x → v = -1/2 cos 2x

∫ x sin 2x = -1/2 x cos 2x - ∫ (-1/2 cos 2x) dx
                = -1/2 x cos 2x + 1/2 ∫ cos 2x dx
                = -1/2 x cos 2x + 1/2 (1/2 sin 2x) + C
                = -1/2 x cos 2x + 1/4 sin 2x + C
                = 1/4 (sin 2x - 2x cos 2x) + C