exponents

2x^-3(x^5-2x^3)
2x^2-4x^0
=2x^2-4

For exponents there are different rules you have to know to solve the problems.  To solve this problem, all you have to do is distribute.  To distribute you multiply the 2x^-3 by everything in the problem.  When you do this, you get 2x^2-4x^0. To multiply exponents, you dont multiply them, you add them together.  So -3 plus 5 equals positive 2 and 2 is you new exponent.  Then you do -3 plus 3 and get 0.  Now your new exponent is zero.  If an exponent is zero, that means there is no exponent.  So you would just get 4.  Your final answer is 2x^2-4. 

(3a^-1)^-1
=1/3a^-1
=3a

To solve this problem, you have to put 3a^-1 over one to take out one of the -1's.  Once you to that, you have to flip it back over and get 3a.