Use the rules of exponents to evaluate and simplify the following expression. type all without negative exponents. (ab)-2 =

For this case we have the following expression:
 (ab) ^ - 2
 Rewriting the expression we have:
 (ab) ^ - 2 = 1 / (ab) ^ 2
 Then, for power properties we have:
 1 / (ab) ^ 2 = 1 / (a ^ 2b ^ 2)

 
 The simplified expression is:
 1 / (a ^ 2b ^ 2)