由于:e^x = 1 + x + x^2/2 + x^3/3! +o(x^3)代入左边,有 左边=1 + (B+1)x + (C+B+1/2)x^2 + (C+B/2+1/6)x^3 + o(x^3)所以有 B+1=A C+B+1/2=0 C+B/2+1/6=0 得: A = 1/3 B = -2/3 C = 1/6
右式的Ax右面是零还是欧
