解 2x2+1 x(x"+ (x2+1)+x x2(x2+1) =+2 +arctan +c 上一页下一页返回解 dx x x x  + + ( 1) 2 1 2 2 2 dx x dx x   + = + 1 1 1 2 2 dx x x x x  + + + = ( 1) ( 1) 2 2 2 2 x C x = − + arctan + 1