^^可以的(1+x^2)sinx-x=(1+x^2)[x-(x^3)/6+o(x^3)]-x=x-(x^3)/6+o(x^3)+x^3-(x^5)/6+o(x^5)-x=(5/6)*x^3-(x^5)/6+o(x^3)+o(x^5)=(5/6)*x^3+o(x^3)