Question

chứng minh rằng:

a) m(n+p)-n(m-p)=(m+n)p

b) m(n-p)-m(n+q)=-m(p+q)

Answer 1

a)Ta có: m(n+p)-n(m-p)

=mn+mp-mn+np

=mp+np

=     (m+n)p       (đpcm)

b)m(n-p)-m(n+p)

=mn-mp-mn-mq

=-mp-mq=-mp+(-mq)

=-m(p+q)       (đpcm)