數學暑假功課 laws of indices 急!!!

simplify the following expressions,where y is a positive integer,and express your answers with positive indices.

1a, 2^y-1+2^y+2/9

1b, 5^3y/25^y-5^2y+1

simplify the following expressions, where x is a positive integer,and express your answers with positive indices.

2a, 3^-2*27^x+1/9^-2x

2b,6^2x/4^x*3^2

simplify the following expressions,where x is a positive integer,and express your answer with positive indices.

3a, (a^2-x)^-2/a^5-x

3b, (2a^3-2x/5a^4x-1)^-2