Line equation from two points, step by step
Two points fix a line.
The question
Write the equation of the line through (1, 4) and (2, 6).
Write the equation of the line through (1, 4) and (2, 6)
slope = (6 − 4) ÷ (2 − 1)
2 ÷ 1=2
b = 4 − (2)(1)=2
y = 2x + 2
- Find the slope first: rise over run, (6 − 4) ÷ (2 − 1) = 2.
- Put a point back in to find b: b = y − mx = 4 − (2)(1) = 2.
- Write it as y = mx + b: y = 2x + 2.
How it works.
- 01
Find the slope first: rise over run, (6 − 4) ÷ (2 − 1) = 2.
- 02
Put a point back in to find b: b = y − mx = 4 − (2)(1) = 2.
- 03
Write it as y = mx + b: y = 2x + 2.