# How do you evaluate the expression for 8*3^x if x=-2 and if x=3?

Jan 6, 2017

See full explanation below.

#### Explanation:

For each of these you Substitute the value for $x$ in the expression.

Problem 1: Solve for $x = - 2$

$8 \cdot {3}^{- 2}$

We can use this rule for exponents to rewrite this problem:

${x}^{\textcolor{red}{a}} = \frac{1}{x} ^ \textcolor{red}{- a}$

$8 \cdot \frac{1}{3} ^ \textcolor{red}{\left(- - 2\right)}$

$8 \cdot \frac{1}{3} ^ \textcolor{red}{2}$

$8 \cdot \frac{1}{9}$

$\frac{8}{9}$

Problem 1: Solve for $x = 3$

$8 \cdot {3}^{3}$

$8 \cdot 27$

$216$