xy-1+x-y 十字相乘法因式分解怎么做啊xy-1+x-y x2y-3xy-2x+6 3x2+4xy+y2

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xy-1+x-y 十字相乘法因式分解怎么做啊xy-1+x-y x2y-3xy-2x+6 3x2+4xy+y2
xy-1+x-y 十字相乘法因式分解
怎么做啊
xy-1+x-y x2y-3xy-2x+6 3x2+4xy+y2

xy-1+x-y 十字相乘法因式分解怎么做啊xy-1+x-y x2y-3xy-2x+6 3x2+4xy+y2
xy-1+x-y
=x(y+1)-(y+1)
=(y+1)(x-1)
x2y-3xy-2x+6
=xy(x-3)-2(x-3)
=(x-3)(xy-2)
3x2+4xy+y2
=(3x+y)(x+y)

第一题和第二题不是用十字相乘法的,用分组分解,第三个可以十字相乘
xy-1+x-y
=xy+x-y-1
=x(y+1)-(y+1)
=(x-1)(y+1)
x^2y-3xy-2x+6
=xy(x-3)-2(x-3)
=(x-3)(xy-2)
3x^2+4xy+y^2
=(x+1)(3x+1)
1 +1
3 +1

x -1
y 1
xy-1+x-y =(x-1)(y+1)
xy -2
x -3
x^2y-3xy-2x+6=(xy-2)(x-3)
x y
3x y
3x^2+4xy+y^2=(x+y)(3x+y)

x -1
y 1
交叉相乘就行了

(x-1)(y+1) (x-3)(xy-2) (3x+y)(x+y)