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f(x)在[0,1]上有二阶导数 f(0)=f(1)=0 f"(x)的绝对值≤M
求证 f'(x)的绝对值≤0.5M
人气:492 ℃ 时间:2019-08-18 00:48:35
解答
任取x,由泰勒公式:f(0)=f(x)+f'(x)(-x)+f''(a)x^2/2f(1)=f(x)+f'(x)(1-x)+f''(b)(1-x)^2/2x相减得:0=f'(x)+f''(b)(1-x)^2/2-f''(a)x^2/2|f'(x)|=|f''(b)(1-x)^2/2-f''(a)x^2/2|《0.5M((1-x)^2+x^2)现考虑g(x)=((1-...
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