Review the exponential notations and practice evaluating natural-number exponents with rational-number bases. Use the multiplication rule to derive the exponent rules: $$x^m \times x^n = x^{m+n}$$ $$\frac{x^m}{x^n} = x^{m-n}$$ $$(x^m)^n = x^{m\times n}$$ $$x^{-n} = {1\over{x^n}}$$ $$x^0 = 1$$