yxy的精选

问题详情：把多项式x2y﹣2xy2+y3分解因式，正确的结果是（）  A．y(x﹣y)2     B．y(x+y)(x﹣y)     C．y(x+y)2   D．y(x2﹣2xy+y2)【回答】A   知识点：因式分解题型：选择题...

问题详情：先化简,再求值:(2x+y)2+(x-y)(x+y)-5x(x-y),其中.【回答】解:(2x+y)2+(x-y)(x+y)-5x(x-y)=4x2+4xy+y2+x2-y2-5x2+5xy=9xy,当x=+1,y=-1时,原式=9×(+1)×(-1)=9×(2-1)=9×1=9.知识点：乘法公式题型：解答题...