# Evaluate \sqrt{b^2 - 4ac} when b = 3, a = -1, c = -2.

## Question:

Evaluate

{eq}\displaystyle \sqrt{b^2 - 4ac} {/eq}

when {eq}\, b = 3 {/eq}, {eq}\, a = -1 {/eq}, {eq}\, c = -2 {/eq}.

## Evaluating Expressions

To evaluate the expression for the given values of the variables, we have to substitute the variables with their values. What this means is that we need to rewrite the expression and instead of writing the variables, we write the value that they are actually taking.

To evaluate the expression for the given values of the variables, we just have to substitute the values given with the variables in the expression. The value will then be:

\begin{align} & \sqrt{3^2 - 4(-1)(-2)}\\ =&\sqrt{9-8}\\ =&\sqrt{1}\\ =&\pm 1 \end{align}