# How do you solve 2x + 1 = 9?

Jul 27, 2015

Isolate $x$ on one side of the equation.

#### Explanation:

In order to solve this equation, you have to isolate$x$ on one side of the equation. You can do that in two steps.

First, add $- 1$ to both sides of the equation

$2 x + \textcolor{red}{\cancel{\textcolor{b l a c k}{1}}} - \textcolor{red}{\cancel{\textcolor{b l a c k}{1}}} = 9 - 1$

$2 x = 8$

Finally, divide both sides of the equation by $2$ to get

$\frac{\textcolor{red}{\cancel{\textcolor{b l a c k}{2}}} \cdot x}{\textcolor{red}{\cancel{\textcolor{b l a c k}{2}}}} = \frac{8}{2}$

$x = \textcolor{g r e e n}{4}$

And there you have it. If you double $x$ and add one, you get nine.