You can put this solution on YOUR website! Your error was in squaring . According to one rule of exponents, you raise a single term, like , to a power by raising each factor to that power. So according to this rule:
becomes
Squaring the -5 is easy. To square the powers of m and n we use another rule of exponents: Multiply the exponents! (This is where you went wrong. You apparently squared the 3 and got 9 and squared the 2 and got 4.) So we should get:
With properly simplified to we can now multiply it by giving us:
P.S. Your answer has n to the right power. But it is only a lucky accident that squaring the exponent of 2 (which you should not have done) works out the same as multiplying the exponents of 2 (which you should have done)!