# How do you solve |9x - 90| = 0?

Sep 21, 2016

Only solution is $x = 10$

#### Explanation:

Note that if $| x = 0 |$, it is either $x = 0$ or $- x = 0$. Bot mean $x = 0$

Similarly $| 9 x - 90 | = 0$ means that absolute value of $9 x - 90$ is zero,

it means either $9 x - 90 = 0$ or $- \left(9 x - 90\right) = 0$

i.e. either $9 x = 90$ or $- 9 x + 90 = 0$

i.e. either $x = \frac{90}{9} = 10$ or $- 9 x = - 90$ and $x = \frac{- 90}{- 9} = 10$

Hence the only solution is $x = 10$