4.3 Point-Slope and Standard Form

Notes

Point-slope form: $y - y_1 = m(x - x_1)$ for a line with slope $m$ through $(x_1, y_1)$.

• Standard form: $Ax + By = C$ with $A$, $B$, $C$ numbers. Find intercepts by setting $x = 0$ or $y = 0$.
• Example: slope 4 through $(2, -1)$: $y + 1 = 4(x - 2)$.
• Watch signs: $y - (-1)$ becomes $y + 1$.
• All forms describe the same line and can be rewritten into each other.