例4x(x2-dk=j(x2-5x2 2- 5x2dx=x2 dx dx 12x2+C 10 x+c 例5[(x-1 3x2+3x dx -×31 x dx-3 dx +3-dx Bx +3 In xI 数学的也数=  25 x dx −  5 21 x dx = 25 x dx − 5 21 = x dx  25 x dx − 5 21 x dx = 25 x dx −5 21 x dx =72 27 x −5·32 23 x +C =72x 3 x − 3 10 x x + C． 例 9  2 3 ( 1) x x − dx = 2 3 2 3 3 1 x x − x + x − dx = (x −3 + x3 − 21x )dx =  x dx −3 dx +3 x1 dx − 21x dx = 21 x 2 −3x +3 ln | x | + x1 + C ． x(x )dx (x x )dx 21 25 2 −5 = −5   例 4 dx x x  −2 3 例 ( 1 ) 5