Question

化简-x2-3x+2x2+4x.xy2-2/3x2y-xy2/2+2x2y.2a

Answer 1

1) --x^2--3x+2x^2+4x

=x^2+x.

2) xy^2--(2/3)x^2y--xy^2/2+2x^2y

=(1/2)xy^2+(4/3)x^2y.

3) 2a--(1/2)ab--(a^2--ab)

=2a--(1/2)ab--a^2+ab

=2a+(1/2)ab--a^2.