例7求ve-1h 2t di 解令Ve-1=t,x=lnt+1,k=+i x=0,t=0,x=ln2,t=1 g小 =20-r中w-2-aamw6-a0 、 例s求f 解令x=sect,d=secttantdt,x=l,t=0,x=2,t= π 3 1414 例 7 求 ln 2 0 1 x e dx −  解 令 2 2 2 1 , ln( 1), 1 x t e t x t dx dt t − = = + = + x t x t = = = = 0, 0; ln2, 1 ln 2 1 2 0 0 2 1 1 x t e dx t dt t − = +   2 1 2 0 1 1 2 1 t dt t + − = +  1 2 0 1 2 (1 ) 1 dt t = − +  1 2( arctan ) 2(1 ) 0 4 t t  = − = − 例 8 求 2 2 1 x 1 dx x −  解 令 sec , sec tan , 1, 0; 2, 3 x t dx t tdt x t x t  = = = = = =