a^n+2+a^n+1-a^n 1/2a^2b^3-2a^2b+3ab^2 -5a^2b^3+20ab^2-5ab 5m(m-n)^4-10mn(n-m)^3 (a+b)y+(

a^n+2+a^n+1-a^n
=a^n×a²+a^n×a-a^n×1
=a^n(a²+a-1)
1/2a^2b^3-2a^2b+3ab^2
=1/2ab×ab²- 1/2ab×4a+ 1/2ab×6b
=1/2ab (ab²-4a+6b)
-5a^2b^3+20ab^2-5ab
=-5ab(ab²-4b+1)
5m(m-n)^4-10mn(n-m)^3
=5m(m-n)^4+10mn(m-n)³
=5m(m-n)³(m-n+2n)
=5m(m-n)³(m+n)
(a+b)y+(b+m)y+(a+m)y
=y(a+b+b+m+a+m)
=2y(a+b+m)