Equation of a Line Through Two Points

Tap a term to see what it means, or .

Calculate

Example: a 5 km taxi ride cost 20, and a 12 km one, 37.50. How much does each kilometre cost, what is the flag fare and how much would a 20 km ride be? Change the values to work out your own case.

x₁ y₁ x₂ y₂ Evaluate at x (optional)

Step by step

What each term means

Slope (m): How much y changes for each unit of x. Positive, the line rises; negative, it falls; zero, it is horizontal. With it and a point comes the intercept b = y₁ − m x₁, and the line is y = mx + b.
How Much y Rises (y₂ − y₁): The vertical change between the two points.
How Far x Moves (x₂ − x₁): The horizontal change. If it is zero, the line is vertical and the slope doesn't exist.