(m+n)(n-m)-n(m+n)(m-n) 2.3a(x-y)-(x-y)a 3.(x-y)²-2(y-x) 4.(m+n)(p+q)-(m+n)(q+p)

问题描述:

(m+n)(n-m)-n(m+n)(m-n) 2.3a(x-y)-(x-y)a 3.(x-y)²-2(y-x) 4.(m+n)(p+q)-(m+n)(q+p)

(m+n)(n-m)-n(m+n)(m-n)
=(m+n)(n-m)+n(m+n)(n-m)
=(1+n)(m+n)(n-m)
2.3a(x-y)-(x-y)a
=2a(x-y)
3.(x-y)²-2(y-x)
=(x-y)²+2(x-y)
=(x-y)(x-y+2)
4.(m+n)(p+q)-(m+n)(q+p)
=(m+n)(p+q)-(m+n)(p+q)
=0