初二下的因式分解(1)(a+b)²-6(a+b)-7=(2)(x-2)²+5(x-2)+4=(3)(a-b)²+3(a-b)(a+b)-10(a+b)²=(4)(x+2y)²-4(x+2y)y-21y²=(5)(x²+x)²-14(x²+x)
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初二下的因式分解(1)(a+b)²-6(a+b)-7=(2)(x-2)²+5(x-2)+4=(3)(a-b)²+3(a-b)(a+b)-10(a+b)²=(4)(x+2y)²-4(x+2y)y-21y²=(5)(x²+x)²-14(x²+x)
初二下的因式分解
(1)(a+b)²-6(a+b)-7=
(2)(x-2)²+5(x-2)+4=
(3)(a-b)²+3(a-b)(a+b)-10(a+b)²=
(4)(x+2y)²-4(x+2y)y-21y²=
(5)(x²+x)²-14(x²+x)+24=
(6)x(x+z)-y(y+z)=
初二下的因式分解(1)(a+b)²-6(a+b)-7=(2)(x-2)²+5(x-2)+4=(3)(a-b)²+3(a-b)(a+b)-10(a+b)²=(4)(x+2y)²-4(x+2y)y-21y²=(5)(x²+x)²-14(x²+x)
1 (a+b+1 )(a+b-7)
2 (x-1 )(x+2)
3 -2(a+3b)(3a-2b)
4 (x+5y)(x-5y)
5 (x-1)(x+2)(x-3)(x+4)
6 (x+y+z)(x-y)
十字相乘法,可以把(a+b)看做x,可解1,2,5
(3)把(a-b)看作x,(a+b)y,可解
(4)a=x+2y
a^2-4ay-21y^2
=(a-7y)(a+3y)
(6)x(x+z)-y(y+z)
=x^2+xz-y^2-yz
=(x+Y)(x-y)+z(x-y)
=(x-y)(x+y+z)
(1)(a+b)²-6(a+b)-7=(a+b+1)(a+b-7)
( 2)(x-2)²+5(x-2)+4=(x-1)(x+2)
(3)(a-b)²+3(a-b)(a+b)-10(a+b)²= -(a+3b)(6a+4b)
(4)(x+2y)²-4(x+2y)y-21y²=(x+5y)(x-5y)
(5)...
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(1)(a+b)²-6(a+b)-7=(a+b+1)(a+b-7)
( 2)(x-2)²+5(x-2)+4=(x-1)(x+2)
(3)(a-b)²+3(a-b)(a+b)-10(a+b)²= -(a+3b)(6a+4b)
(4)(x+2y)²-4(x+2y)y-21y²=(x+5y)(x-5y)
(5)(x²+x)²-14(x²+x)+24=(x-1)(x+2)(x-3)(x+4)
(6)x(x+z)-y(y+z)=(x-y)(x+y+z)
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