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几道初二因时化简计算（十字相乘法）4.a^2+7ab+12b5.(x-y)^2-5(x-y)-366.(x^2+3x)^2-8(x^2+3x)-207.2a^2-11a+12题号标错
题目详情
几道初二因时化简计算
（十字相乘法）
4.a^2+7ab+12b
5.(x-y)^2-5(x-y)-36
6.(x^2+3x)^2-8(x^2+3x)-20
7.2a^2-11a+12
题号标错
（十字相乘法）
4.a^2+7ab+12b
5.(x-y)^2-5(x-y)-36
6.(x^2+3x)^2-8(x^2+3x)-20
7.2a^2-11a+12
题号标错
▼优质解答
答案和解析
4.a^2+7ab+12b
=(a+3b)(a+4b)
5.(x-y)^2-5(x-y)-36
=(x-y-9)(x-y+4)
6.(x^2+3x)^2-8(x^2+3x)-20
=(x^2+3x-10)(x^2+3x+2)
=(x-2)(x+5)(x+1)(x+2)
7.2a^2-11a+12
=(2a-3)(a-4)
=(a+3b)(a+4b)
5.(x-y)^2-5(x-y)-36
=(x-y-9)(x-y+4)
6.(x^2+3x)^2-8(x^2+3x)-20
=(x^2+3x-10)(x^2+3x+2)
=(x-2)(x+5)(x+1)(x+2)
7.2a^2-11a+12
=(2a-3)(a-4)
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