# What is the equation of the line that goes through point (3,-1) and has a slope = -1?

Sep 24, 2016

Use the point-slope form, $y - {y}_{1} = m \left(x - {x}_{1}\right)$

#### Explanation:

Substitute $3$ for ${x}_{1}$, $- 1$ for ${y}_{1}$, and $- 1$ for $m$.

$y - \left(- 1\right) = \left(- 1\right) \left(x - 3\right)$

$y + 1 = \left(- 1\right) \left(x - 3\right)$

Distribute the $- 1$ through the parentheses:

$y + 1 = 3 - x$

Subtract $1$ from both sides:

$y = 2 - x$

Done