作函数图像：

y=log1/21/x*2

作函数图像：

y=2/45x^2+75

作函数图像：

y=√（2²-x²）

作函数图像：

y=cos(x-π/2)+cos(3x-π/2)

作函数图像：

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y=xcosxx
y=xsinx