f(x)在(-∞,+∞)有定义,y=f(x^2)为什么为偶函数
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偶函数必须是 f(-x)=f(x)而y=f(x²)=f[(-x)²]所以是偶函数。
解你好设F(x)=f(x^2）
则由题知x属于R.
欲求y=f(x^2)为什么为偶函数
故只需证明F(x)是偶函数，
而F(-x)=f(（-x）^2)=f(x^2)=F(x)
即F(x)是偶函数，
故y=f(x^2)为偶函数。
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