Question

先去括号,再合并同类项.(x+2Y)-(2x-y)=( ) 6m-3(-m+2n)=( ) a^2+2(a^2-a)-4

Answer 1

x+2Y-2x+y=3y-x

6m+3m-6n=9m-6n

a^2+2(a^2-a)-4(a^2-3a)=a^2+2a^2-2a-4a^2+12a=8a-a^2