万急!几道初一十字交叉法的因式分解题1.（x^2+4x）^2-x^2-4x-202.m^2+11n-mn-11m3.9-a^2-b^2-2ab4.9m^2-6m+2n-n^25.ax^2-bx^2-bx+ax+a-b6.x^3+2xy-x-xy^27.a^2+2ab+b^2-2a-2b+1

万急!几道初一十字交叉法的因式分解题1.（x^2+4x）^2-x^2-4x-202.m^2+11n-mn-11m3.9-a^2-b^2-2ab4.9m^2-6m+2n-n^25.ax^2-bx^2-bx+ax+a-b6.x^3+2xy-x-xy^27.a^2+2ab+b^2-2a-2b+1
万急!几道初一十字交叉法的因式分解题
1.（x^2+4x）^2-x^2-4x-20
2.m^2+11n-mn-11m
3.9-a^2-b^2-2ab
4.9m^2-6m+2n-n^2
5.ax^2-bx^2-bx+ax+a-b
6.x^3+2xy-x-xy^2
7.a^2+2ab+b^2-2a-2b+1

万急!几道初一十字交叉法的因式分解题1.（x^2+4x）^2-x^2-4x-202.m^2+11n-mn-11m3.9-a^2-b^2-2ab4.9m^2-6m+2n-n^25.ax^2-bx^2-bx+ax+a-b6.x^3+2xy-x-xy^27.a^2+2ab+b^2-2a-2b+1
1.（x^2+4x）^2-x^2-4x-20
=(x^2+4x)^2 - (x^2+4x) -20
=[(x^2+4x)-5)][(x^2+4x)+4]
=(x+5)(x-1)(x+2)^2
2.m^2+11n-mn-11m
=(m^2-11m) -(mn-11n)
=m(m-11)-n(m-11)
=(m-11)(m-n)
3.9-a^2-b^2-2ab
=9-(a^2+2ab+b^2)
=3^2-(a+b)^2
=(3+a+b)(3-a-b)
4.9m^2-6m+2n-n^2
=(9m^2-6m+1)-(n^2-2n+1)
=(3m-1)^2-(n-1)^2
=(3m-1+n-1)(3m-1-n+1)
=(3m+n-2)(3m-n)
5.ax^2-bx^2-bx+ax+a-b
=x^2(a-b)+x(a-b)+(a-b)
=(a-b)(x^2+x+1)
6.x^3+2xy-x-xy^2
=x(x^2-y^2+2y-1)
=x[x^2-(y-1)^2]
=x(x+y-1)(x-y+1)
7.a^2+2ab+b^2-2a-2b+1
=(a+b)^2-2(a+b)+1
=(a+b-1)^2

1.（x^2+4x）^2-x^2-4x-20
=（x^2+4x）^2-(x^2+4x)-20
=(x^2+4x-5)(x^2+4x+4)
=(x-5)(x+1)(x+2)^2
2.m^2+11n-mn-11m
=m(m-11)-n(m-11)
=(m-n)(m-11)
3.9-a^2-b^2-2ab
=9-(a+b)^2
=(...

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1.（x^2+4x）^2-x^2-4x-20
=（x^2+4x）^2-(x^2+4x)-20
=(x^2+4x-5)(x^2+4x+4)
=(x-5)(x+1)(x+2)^2
2.m^2+11n-mn-11m
=m(m-11)-n(m-11)
=(m-n)(m-11)
3.9-a^2-b^2-2ab
=9-(a+b)^2
=(3+a+b)(3-a-b)
4.9m^2-6m+2n-n^2
=9m^2-6m+1-1+2n-n^2
=(3m-1)^2-(n-1)^
=(3m-1+n-1)(3m-1-n+1)
5.ax^2-bx^2-bx+ax+a-b
=(a-b)(x^2+x+1)
6.x^3+2xy-x-xy^2
=题目对吗
7.a^2+2ab+b^2-2a-2b+1
=(a+b)^2-2(a+b)+1
=(a+b-1)^2

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1.(x^2+4x)^2-x^2-4x-20
=(x^2+4x)^2-(x^2+4x)-20
=[(x^2+4x)-5][(x^2+4x)+4]
=(x+5)(x-1)(x+2)^2
2.m^2+11n-mn-11m
=（m-11）m-(m-11)n
=(m-11)（m-n）
3.9-(a^2+2ab+b^2)
=9-(a+b)^2...

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1.(x^2+4x)^2-x^2-4x-20
=(x^2+4x)^2-(x^2+4x)-20
=[(x^2+4x)-5][(x^2+4x)+4]
=(x+5)(x-1)(x+2)^2
2.m^2+11n-mn-11m
=（m-11）m-(m-11)n
=(m-11)（m-n）
3.9-(a^2+2ab+b^2)
=9-(a+b)^2
=(3+a+b)(3-a-b)
4.9m*2-6m+2n-n^2
=9m^2-6m+2n-n^2
=(3m)^2-6m+2n-n^2
=[(3m-1)^2-1]-[(n-1)^2-1]
=[(3m-1)^2+(n-1)^2-2][(3m-1)^2-(n-1)^2]
=[(3m-1)^2+(n-1)^2-2](3m+n-2)(3m-n)
5.ax^2-bx^2-bx+ax+a-b
=(a-b)x²-（a-b）x+（a-b）
=（a-b）（x²-x+1）
6.x^3+2xy-x-xy^2
=x^3-x(y-1)^2
=x(x^2-(y-1)^2)
=x(x-y+1)(x+y-1)
7.a^2+2ab+b^2-2a-2b+1
=(a^2+2ab+b^2)-2(a+b)+1
=(a+b)^2-2(a+b)+1
=（a+b-1）^2

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1.（x^2+4x）^2-x^2-4x-20
=（x^2+4x）^2-(x^2+4x)-20
=(x^2+4x-5)(x^2+4x+4)
=(x+5)(x-1)(x+2)^2
2.m^2+11n-mn-11m
=m^2-mn-11m+11n
=m(m-n)-11(m-n)
=(m-n)(m-11)
3.9-a^2-b^2-2ab

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1.（x^2+4x）^2-x^2-4x-20
=（x^2+4x）^2-(x^2+4x)-20
=(x^2+4x-5)(x^2+4x+4)
=(x+5)(x-1)(x+2)^2
2.m^2+11n-mn-11m
=m^2-mn-11m+11n
=m(m-n)-11(m-n)
=(m-n)(m-11)
3.9-a^2-b^2-2ab
=9-(a+b)^2
=(a+b+3)(3-a-b)
4.9m^2-6m+2n-n^2
=9m^2-6m+1+2n-n^2-1
=(3m-1)^2-(n-1)^2
=(3m-1+n-1)(3m-1-n+1)
=(3m+n-2)(3m-n)
5.ax^2-bx^2-bx+ax+a-b
=x^2(a-b)+x(a-b)+a-b
=(a-b)(x^2+x+1)
6.x^3+2xy-x-xy^2
=x(x^2+2y-1-y^2)
=x[x^2-(y-1)^2]
=x(x+y-1)(x-y+1)
7.a^2+2ab+b^2-2a-2b+1
=(a+b)^2-2(a+b)+1
=(a+b-1)^2

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