昨天一个本科学妹问我一道数学题, 她觉得有些困惑. 题目是道选择题, 具体如下:The function $f(x,y)=3x^2y+y^3-3x^2-3y^2+2$has a saddle point at (-1,1)has a minimum point at (-1,1)has a maximum point at (0,2)has four minimum points

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