3 2 例4求积分 ∫(1 1、2)dt 解∫( 3 2 1+x =3 1+x d-2「 1-x 3arctanx-2arcsinx +C Economic-mathematics 19-12 Wednesday, February 24, 2021Economic-mathematics 19- 12 Wednesday, February 24, 2021 例4 求积分 解 ) . 1 2 1 3 ( 2 2 dx x x  − − + dx x x ) 1 2 1 3 (  2 2 − − + dx x dx x   − − + = 2 2 1 1 2 1 1 3 = 3arctanx − 2arcsinx + C