令g(x) = a0x + a1/2 x² + ...+an/(n+1) x^(n+1)
则 g(0)=g(1) = 0
由罗尔中值定理有
存在c∈(0,1),使得 g'(c) = f(c) = 0
得证
更清晰的答案,见下
www.duodaa.com/?qa=3040/