解1题
原式=(x+y)[(x-y)-(x+y)]
=(x+y)(x-y-x-y)
=(x+y)×(-2y)
=-2y(x+y)
解2题
原式=3m(m-n)-6n(m-n)
=3(m-n)(m-2n)
解3题
原式=x(x-y)+y(x-y)
=(x-y)(x+y)
解4题
原式=(x-3)²+3(x-3)
=(x-3)[(x-3)+3]
=x(x-3)
解1题
原式=(x+y)[(x-y)-(x+y)]
=(x+y)(x-y-x-y)
=(x+y)×(-2y)
=-2y(x+y)
解2题
原式=3m(m-n)-6n(m-n)
=3(m-n)(m-2n)
解3题
原式=x(x-y)+y(x-y)
=(x-y)(x+y)
解4题
原式=(x-3)²+3(x-3)
=(x-3)[(x-3)+3]
=x(x-3)