Exponent laws
Multiplying adds exponents; dividing subtracts them; a power of a power multiplies them.
A worked example
Simplify x^5 / x^2. Subtract the exponents: 5 - 2 = 3, so the answer is x^3.
The mistake people actually make
A negative exponent means one over, so x^-2 = 1/x^2. It does not make the answer negative.