因式分解(十字相乘法) ①5x²-7x+2 ②7(a+b)²-6(a+b)-1③3a²bˆ 3+ab²-2b④xyˆ3-3x²y
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![因式分解(十字相乘法) ①5x²-7x+2 ②7(a+b)²-6(a+b)-1③3a²bˆ 3+ab²-2b④xyˆ3-3x²y](/uploads/image/z/1325233-1-3.jpg?t=%E5%9B%A0%E5%BC%8F%E5%88%86%E8%A7%A3%EF%BC%88%E5%8D%81%E5%AD%97%E7%9B%B8%E4%B9%98%E6%B3%95%EF%BC%89+%E2%91%A05x%26%23178%3B-7x%2B2+%E2%91%A17%EF%BC%88a%2Bb%29%26%23178%3B-6%EF%BC%88a%2Bb%29-1%E2%91%A23a%26%23178%3Bb%26%23710%3B+3%2Bab%26%23178%3B-2b%E2%91%A3xy%26%23710%3B3-3x%26%23178%3By)
因式分解(十字相乘法) ①5x²-7x+2 ②7(a+b)²-6(a+b)-1③3a²bˆ 3+ab²-2b④xyˆ3-3x²y
因式分解(十字相乘法) ①5x²-7x+2 ②7(a+b)²-6(a+b)-1③3a²bˆ 3+ab²-2b④xyˆ3-3x²y
因式分解(十字相乘法) ①5x²-7x+2 ②7(a+b)²-6(a+b)-1③3a²bˆ 3+ab²-2b④xyˆ3-3x²y
1 -1
5 -2
5x²-7x+2=(x-1)(5x-2)
1 -1
7 1
(a+b)²-6(a+b)-1=[(a+b)-1][7(a+b)+1]=(a+b-1)(7a+7b+1)
3a²b³+ab²-2b
=b(3a²b²+ab-2)
1 1
3 -2
3a²b³+ab²-2b=b(3a²b²+ab-2)=b(ab+1)(3ab-2)
xy³-3x²y=xy(y²-3x)