例23.y=3x+x3+3+x,求y 解:y=(3)y+(x3)y+(3)+(x 3-In3+3x2+0+exIn x(xn x) 3ln3+3x2+x(nx+1)结束 解 =3 x ln3+3x 2+0+e xln x (xln x) =3 x ln3+3x 2+x x (ln x+1) 例23 y=3 x+x 3+3 3+x x  求y y=(3x )+(x 3 )+(33 )+(x x )