(2x-y-1)(2x+y+1)
来源:百度知道 编辑:UC知道 时间:2024/05/28 11:47:58
(2x-y-1)(2x+y+1)
=4x^2+2xy+2x-2xy-y^2-y-2x-y-1
=4x^2-y^2-2y-1
不必按死方法硬算,可以借助平方差公式。
解:
(2x-y-1)(2x+y+1)
=[2x-(y+1)][2x+(y+1)]
=4x²-(y+1)²
=4x²-(y²+2y+1)
=4x²-y²-2y-1
<(2x-y)-1><(2x+y)+1>
=(2x-y)(2x+y)+2x-y-(2x+y)-1
=4x^2-y^2-2y-1
肯定是发起投票
回答者:翠雨黄山 - 都司 七级 排在第一
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