∫(x2-5t=x-5r =jx-可x -9c =子G-9xwF+C %。求 解： h=j-n+-h x -j-3+ 2 3 -号-3x+h++C 例7.求「(e-3cosx+2e)k [(e*-3cosx+2*e*)dx =∫e'k-3 [cosxdx+∫(2e)'k eC =e-3m++c 制求先后 解： ∫-t芳 1+x+x2 =+小 In |x|+arctanx+Cx x x x C x x C x dx x dx x x dx x x dx = − + = − + = − − = −     3 10 7 2 3 10 7 2 5 ( 5) ( 5 ) 3 2 3 2 7 2 1 2 5 2 1 2 5 2 例6． 求 dx x x  − 2 3 ( 1) 解： C x x x x x x C dx x x x dx x x x x dx x x = − + + + = − + = − + − − + − = −    1 3 3ln | | 2 3 10 7 2 ) 3 1 ( 3 ( 1) 3 3 1 2 2 3 2 7 2 2 3 2 2 3 例7． 求  e − x + e dx x x x ( 3cos 2 ) 解： C e e x C e e e x e dx xdx e dx e x e dx x x x x x x x x x + + = − + = − + + = − + − +     1 ln 2 (2 ) 3sin ln( 2 ) (2 ) 3sin 3 cos (2 ) ( 3cos 2 ) 例 8．求 dx x x x x  + + + (1 ) 1 2 2 解： x x C dx x dx x dx x x x x dx x x x x = + + + = + + + + = + + +     ln | | arctan 1 1 1 (1 ) (1 ) (1 ) 1 2 2 2 2 2