Question

初一数学计算

（2a+1)²-（1-2a)²
（2x+y-1)(2x-y+1)
a(a-2b）-（a-b)²
快快快，要过程

Answer 1

（2a+1)²-（1-2a)²
=（2a+1+1-2a）(2a+1-1+2a)
=2*4a
=8a

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

a(a-2b）-（a-b)²
=a^2-2ab-a^2+2ab-b^2
=-b^2

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Answer 2

（2a+1)²-（1-2a)²=（2a+1+1-2a）（2a+1-1+2a）=2×4a=8a
(2x-y+1)(2x+y-1)=[2x-(y-1)][2x+(y-1)]=(2x)²-(y-1)²=4x²-y²+2y-1
a(a-2b）-（a-b)²=a²-2ab-(a²-2ab+b²)=a²-2ab-a²+2ab-b²=-b²
望采纳。望采纳。

Answer 3

（2a+1)²-（1-2a)² = （2a+1+1-2a)[2a+1-(1-2a)]=2*4a= 8a
（2x+y-1)(2x-y+1) = [2x+(y-1)][2x-(y-1)] = 4x²-(y-1)²=4x²-y²-1+2y
a(a-2b）-（a-b)²=a²-2ab-（a²- 2ab+b²) = -b²

Answer 4

(2a+1)²-(1-2a)²
=[2a+1+(1-2a)]*[2a+1-(1-2a)]
=8a

(2x+y-1)*(2x-y+1)
=[2x+(y-1)]*[2x-(y-1)]
=(2x)²-(y-1)²
=4x²-y²+2y-1

a(a-2b)-(a-b)²
=a²-2ab-(a-b)²+b²-b²
=(a-b)²-(a-b)²-b²
=-b²

自己好好检查啊。。看懂配方= -

Answer 5

(1)4a²+4a+1-4a²+4a-1=8a
(2)4x²-2xy+2x+2xy-y²+y-2x+y-1=4x²-y²+2y-1
(3)a²-2ab-(a²-2ab+b²)=a²-2ab-a²+2ab-b²=b²

Answer 6

4a²+4a+1-1+4a-4a²=8a

4x²-2xy+2x+2xy-y²+y-2x+y-1=4x²-y²+y-1

a²-2ab-a²+2ab+b²