求不定积分 ∫( xarctanx)dx=
3个回答

∫ xarctanx dx

= ∫ arctanx d(x²/2)

= (x²/2)arctanx - (1/2)∫ x² d(arctanx)

= (1/2)x²arctanx - (1/2)∫ x²/(x² + 1) dx

= (1/2)x²arctanx - (1/2)∫ [(x² + 1) - 1]/(x² + 1) dx

= (1/2)x²arctanx - (1/2)∫ dx + (1/2)∫ dx/(x² + 1)

= (1/2)x²arctanx - x/2 + (1/2)arctanx + C