Question

计算：(-3/4)*(1又1/2)/(-2又1/4)

Answer 1

(-3/4)*(1又1/2)/(-2又1/4)

=-3/4*3/2/(-9/4)

=-9/8*(-4/9)

=1/2

（1）15ab^2-3a^2 b-8ab^2-21a^2 b

=(15-8)ab^2-(3+21)a^2 b

=7ab^2-24a^2 b

（2）1/4（m+2n)^2-5(m-n)-1/2(m+2n)^2+3(m-n)

=(1/4-1/2)(m+2n)^2-(5-3)(m-n)

=-1/4(m+2n)^2-2(m-n)