分解因式:(1)(x-y)(x-y-2)+1= (2)(a平方-b平方)+4(b-1)= (3)9(x-y)平方+42(x-y)+49=

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分解因式:(1)(x-y)(x-y-2)+1= (2)(a平方-b平方)+4(b-1)= (3)9(x-y)平方+42(x-y)+49=
分解因式:(1)(x-y)(x-y-2)+1= (2)(a平方-b平方)+4(b-1)= (3)9(x-y)平方+42(x-y)+49=

分解因式:(1)(x-y)(x-y-2)+1= (2)(a平方-b平方)+4(b-1)= (3)9(x-y)平方+42(x-y)+49=
1
=(x-y)²-2(x-y)+1
=(x-y+1)²
2
=a²-b²+4b-4
=a²-(b-2)²
=(a+b-2)(a-b+2)
3
=(3x-3y)²+2(3x-3y)×7+7²
=(3x-3y+7)²

(1)
(x-y)(x-y-2)+1=(x-y)^2-2(x-y)+1=(x-y-1)^2
(2)
a^2-b^2+4b-4=a^2-(b-2)^2=(a-b+2)(a+b-2)
(3)9(x-y)^2+42(x-y)+49
=[3(x-y)]^2+2*3*7(x-y)=7^2
=[3(x-y)+7]^2

一个= 2时,b =2√3
渐近线为Y =±√3x
渐近线,因此,x轴之间的角度为θ
tanθ=√3,θ= 60°
所以两条渐近线之间的夹角为2θ= 120°或180°-2θ= 60°
所以角为120°或60°