计算(2x+y+1)(2x+y-1)

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计算(2x+y+1)(2x+y-1)

计算(2x+y+1)(2x+y-1)
计算(2x+y+1)(2x+y-1)

计算(2x+y+1)(2x+y-1)
(2x+y+1)(2x+y-1)
=[(2x+y)+1][(2x+y)-1]
=(2x+y)^2-1
=4x^2+4xy+y^2-1

(2x+y+1)(2x+y-1)
=(2x+y)^2-1
=4x^2+4xy+y^2-1

把2x+y看做整体
然后就是(2x+y)的平方-1
答案就是4x的平方+4xy+y的平方-1

(2x+y+1)(2x+y-1)=(2x+y)^2-1=4x^2+y^2+4xy-1