åå¼=1/2*â«arctanxd(x^2)=1/2*x^2*arctanx-1/2*â«x^2d(arctanx)
=1/2*x^2*arctanx-1/2*â«x^2/(1+x^2)*dx
=1/2*x^2*arctanx-1/2*â«[1-1/(1+x^2)]dx
=1/2*x^2*arctanx-1/2*x+arctanx+C ã
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追çä¹å· ã1/2x æä½ ç解æ 1/(2x) äºï¼æ以ç¹æå äºä¸ª * .