整式的除法.我马上就要去补课了.

1.原式=（x^2+2x-x-2+2)÷x=x+1
2.原式=（6^an+2-9an+1)÷3^an-1
=（2^an+2)x3^(an+2-an+1)-3^2(an+1)÷3^an-1
=3^3（2^an+3)-3^(2an+2-an+1)
=3^3（2^an+2)-3^(an+3)+1
3.原式=9x^4-18x^3y-(3y^2-4x^3y)
=9x^4-14x^3y-3y^2
4.原式=[x^2-y^2-(x^2-2xy+y^2)+2xy-2y^2]÷4y
=(x^2-y^2-x^2+2xy-y^2+2xy-2y^2)÷4y
=(4xy-4y^2)÷4y
=x-y