# How do you solve the equation x^2-324=0?

Oct 1, 2017

Given: ${x}^{2} - 324 = 0$

Add 324 to both sides:

${x}^{2} = 324$

Use the square root on both sides:

$x = \pm 18$

This means that the solutions are $x = 18 \mathmr{and} x = - 18$

Oct 1, 2017

$x = 18$

#### Explanation:

${x}^{2} - 324 = 0$
${x}^{2} = 324 = 18 \cdot 18 = {18}^{2}$
$\therefore x = 18$

Oct 1, 2017

$x = 18 \mathmr{and} x = - 18$

#### Explanation:

This can be solved by factorising the quadratic using the difference of two squares.

${x}^{2} - 324 = 0$

$\left(x + 18\right) \left(x - 18\right) = 0$

Set each factor equal to $0$

$x + 18 = 0 \text{ } \rightarrow x = - 18$

$x - 18 = 0 \text{ } \rightarrow x = 18$