Question 22969
Have you done anything with the laws of exponents?  For example, when you divide with the same base number, you subtract exponents:  
{{{(x^12)/(x^5)= x^7 }}}


If it had been {{{(x^5)/(x^12)}}} can you see that if you subtract exponents you would have {{{x^(5-12)}}} which could be written {{{x^(-7)}}}?


This same problem {{{(x^5)/(x^12)}}} could also be simplified as a fraction to be reduced by dividing out the five x factors in the numerator with five of the x factors in the denominator.  In this method, all the x factors in the numerator divide out, and you would be left with a 1 in the numerator since they all divided out and seven factors of x left in the denominator:  
{{{1/x^7}}}  


What you have just done is derived the formula {{{x^(-7)= 1/(x^7)}}}


In summary, any time you have a negative exponent, you get a fraction whose numerator is 1, and whose denominator is the same as the original problem but with a positive exponent.  For examples:
{{{x^(-2)= 1/(x^2)}}}


{{{x^(-3)= 1/(x^3)}}}


R^2 at SCC