Write the number 1 followed by a fraction sign: /.
Move the term or terms with negative exponents to the denominator (bottom position) of the fraction. For instance, you would factor x^-3 + x^-5 as 1/x^-3 + x^-5.
Remove the negative signs from the exponents once you have shifted them to the denominator. In this example, you would write 1/x^3 + x^5.
Combine like terms if possible. For example, if you had 2x^-4 + x^-4, you would create the fraction 1/2x^4 + x^4. Since both terms of the binomial are alike (some quantity of x^4), you can add them to get a factored answer of 1/3x^4.