1+e 解 1+e2-e2 = 1+c 1+ x d 1+e d(1+e2) 1+e x-In(1+e)+c 202//30 ll2021/1/30 11  + x e dx 1 [例5] dx e e e dx e x x x  x  + + − = + 1 1 1 1 dx e e dx x x   + = − 1  + + = − x x e d e x 1 (1 ) [解] x e C x = − ln(1+ ) +