Question

一些数学题..急啊

（2s+1)-3(s^2-s+2)
-2(a^2b-1/4ab^2+1/2a^3)-(-2a^2b+3ab^2)
-1/2(5mn-2m^2+3n^2)+-3/2mn+2m^2+n^2/2
(a^3+1/5a^2b+3-1/2(a^2b-6)

Answer 1

（2s+1)-3(s^2-s+2)=2s+1-3s^2+3s-6=-3s^2+5s-5

-2(a^2b-1/4ab^2+1/2a^3)-(-2a^2b+3ab^2)
=-2a^2b+1/2ab^2-a^3+2a^2b-3ab^2
=(-2+2)a^2b+(1/2-3)a^2b-a^3
=-a^3-5/2ab^2

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

(a^3+1/5a^2b+3-1/2(a^2b-6)
=a^3+1/5a^2b+3-1/2a^2b+3
=a^3+(1/5-1/2)a^2b+6
=a^3-3/10a^2b+6

Answer 2

哪有什么题啊？