分解因式:7xx-3y+xy-21x

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分解因式:7xx-3y+xy-21x
分解因式:7xx-3y+xy-21x

分解因式:7xx-3y+xy-21x
原式:7xx-3y+xy-21x
=(7xx-21x )+(xy-3y)
=7x(x-3)+y(x-3)
=(7x+y)(x-3)

=7x(x-3)+y(x-3)
=(x-3)(7x+y)

7xx-3y+xy-21x=(7xx+xy)-(3y+21x)=X(7x+y)-3(y+7x)=(x-3)(7x+y)

=7xx-21x+xy-3y=7x(x-3)+y(x-3)=(x-3)(7x+y)