## Algebra 1

$y - y_{1} = m (x - x_{1})$ (starting in point slope form) $y - y_{1} = m*x - m*x_{1}$ (expanding the right side of the equation) $y - y_{1} = mx - mx_{1}$ (simplifying the right side of the equation) $y - y_{1} (+y_{1}) = mx - mx_{1} (+y_{1})$ (adding y_{1} to both sides to solve for y) $y = mx - mx_{1} +y_{1}$ $m, x_{1}$, and $y_{1}$ are all numbers (constants), so we can calculate the combined value of these constants. Let $b$ be the sum of $mx_{1} +y_{1}$. Thus, we can make the following conversion. $y = mx - mx_{1} +y_{1}$ $y = mx (- mx_{1} +y_{1})$ $y = mx + b$