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# Linear equations

### The linear equation and straight line graphs

• Linear functions are functions whose graphs represent straight lines.
• Linear equations can be recognised by the slope-intercept formula:
$y = mx + c$ where $$m$$ is the slope (or gradient) of the line and $$c$$ is the $$y$$-intercept.
• Sometimes you will need to rearrange the equation so that it is in the slope-intercept formula. For example:
\begin{eqnarray*}
2y - 4x &=& 10 \\
2y &=& 10 + 4x \\
y &=& \frac{10+4x}{2} \\
y &=& \frac{10}{2}+ \frac{4}{2}x \\
y &=& 5 + 2x \\
y &=& 2x + 5
\end{eqnarray*}
• You can graph linear functions by drawing up a table of values and then plotting the points.