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f(x)=3x^2+x是否是凹函数

回复(1) 2010-08-12 10:49 来自版块 -

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: teacher2：解答：作差f[(x1+x2)/2]-[f(x1)+f(x2)]/2 =3[(x1+x2)/2]^2+(x1+x2)/2-(3x1^2+x1+3x2^2+x2)/2 =3[(x1+x2)/2]^2-(3x1^2+3x2^2)/2 =(3/4)(2x1x2-x1^2+x2^2)...(2010-08-12 11:05)

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