x³y-4xy³=xy(x²-4y²)=xy(x+2y)(x-2y) 5x(a+b)-y(b+a)公因式是(a+b)=5x(a+b)-y(a+b)=(5x-y)(a+b) 3(x-2)-2x(2-x)=3(x-2)+2x(x-2)=(3+2x)(x-2)很高兴为您解答,祝你学习进步!【the 190...客气了！