作业帮初一计算(过程详细)完全平方公式
来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/05/16 05:10:10
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
(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
(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^2
=9y^2-8xy
(5).63^2
=(60+3)^2
=60^2+2*60*3+3^2
=3600+360+9
=3969
(6).998^2
=(1000-2)^2
=1000^2-2*1000*2+2^2
=1000000-4000+4
=996000+4
=996004
(7).(a+b)^3
=a^3+3a^2b+3ab^2+b^3
=(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^2
=9y^2-8xy
(5).63^2
=(60+3)^2
=60^2+2*60*3+3^2
=3600+360+9
=3969
(6).998^2
=(1000-2)^2
=1000^2-2*1000*2+2^2
=1000000-4000+4
=996000+4
=996004
(7).(a+b)^3
=a^3+3a^2b+3ab^2+b^3