Point-slope equation of a line, step by step
Given the slope and one point, writing y = mx + b comes down to a single unknown: the intercept.
The question
Write the equation of the line with slope 2 through (3, 8).
Write the equation of the line with slope 2 through (3, 8)
m = 2
b = 8 − (2)(3)=2
y = 2x + 2
- The slope is given: m = 2. Now find where the line crosses the y-axis.
- Put a point back in to find b: b = y − mx = 8 − (2)(3) = 2.
- Write it as y = mx + b: y = 2x + 2.
How it works.
- 01
The slope is given: m = 2. Now find where the line crosses the y-axis.
- 02
Put a point back in to find b: b = y − mx = 8 − (2)(3) = 2.
- 03
Write it as y = mx + b: y = 2x + 2.