求解初一用十字相乘法分解因式的题
1。 2*（x+y）^2+(x+y)(c+d)-6（c+d）^2
=2(x+y)^2+4(x+y)(c+d)-3(x+y)(c+d)-6(c+d)^2
=2(x+y)((x+y)+2(c+d))-3(c+d)((x+y)+2(c+d))
=((x+y)+2(c+d))(2(x+y)-3(c+d))
2。 21a^2-13ab+2b^2
=21a^2-7ab-6ab+2b^2
=7a(3a-b)-2b(3a-b)
=(3a-b)(7a-2b)
3。 (x-y)^2-3(x-y)-10
=(x-y)^2-5(x-y)+2(x-y)-10
=(x-y)(x-y-5)+2(x-y-5)
=(x...全部
1。 2*（x+y）^2+(x+y)(c+d)-6（c+d）^2
=2(x+y)^2+4(x+y)(c+d)-3(x+y)(c+d)-6(c+d)^2
=2(x+y)((x+y)+2(c+d))-3(c+d)((x+y)+2(c+d))
=((x+y)+2(c+d))(2(x+y)-3(c+d))
2。
21a^2-13ab+2b^2
=21a^2-7ab-6ab+2b^2
=7a(3a-b)-2b(3a-b)
=(3a-b)(7a-2b)
3。 (x-y)^2-3(x-y)-10
=(x-y)^2-5(x-y)+2(x-y)-10
=(x-y)(x-y-5)+2(x-y-5)
=(x-y-5)(x-y+2)
4。
x^(n+1)-3x^n+2x^(n+2)
=x^n*x-3x^n+2x^n*x^2
=x^n(x-3+2x^2)
=x^n(2x^2+3x-2x-3)
=x^n(x(2x+3)-(2x+3))
=x^n(2x+3)(x-1)
。
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