相關2xy2x的文學知識

先化簡,再求值:(2x+y)2+(x-y)(x+y)-5x(x-y),其中.

先化簡,再求值:(2x+y)2+(x-y)(x+y)-5x(x-y),其中.

問題詳情:先化簡,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,當x=+1,y=-1時,原式=9×(+1)×(-1)=9×(2-1)=9×1=9.知識點:乘法公式題型:解答題...