初一计算(过程详细)完全平方公式
(1).(2x+y+1)(2x+y-1)
(2).(x-2)(x+2)-(x+1)(x-3)
(3).(ab+1)^2-(ab-1)^2
(4).(2x-y)^2-4(x-y)(x+2y)
(5).63^2
(6).998^2
(7).(a+b)^3
人气：229 ℃ 时间：2020-03-12 03:11:07
解答
(1).(2x+y+1)(2x+y-1) =(2x+y)^2-1=4x^2+4xy+y^2-1(2).(x-2)(x+2)-(x+1)(x-3) =x^2-4-x^2+2x+3=2x-1(3).(ab+1)^2-(ab-1)^2 =(ab+1+ab-1)(ab+1-ab+1)=2ab*2=4ab(4).(2x-y)^2-4(x-y)(x+2y) =4x^2-4xy+y^2-4x^2-4xy+8y^...
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