例8求 解 (x-a)(x+a) dx Inlx-a-Inlx+a+C 2ax-a x+a d 例9求 x(1+2Inx 解∫ d x din x d2 Inx x+2n)-」(+2m)=2(+2m I rd(1+2In x 2(1+2lnx)-2 In/1+2Inx+c. 1  2 2 − x x a 求 d  − x x a d 2 2 1  − + = x x a x a d ( )( ) 1    + − − = x a x a x a d 1 1 21 (ln ln ) . 21 x a x a C a = − − + + 例 8 解 ( ) . 1 2ln  x + x dx 求 ( )  x + x x 1 2ln d ( )  + = x x 1 2ln d ln ( )  + = xx 1 2ln 2ln 21 d ( )  ++ = xx 1 2ln ( 1 2ln ) 21 d ln 1 2ln . 21 = + x + C 例 9 解