Brainlag PlusFind m, then substitute a point to find c: from a gradient and a point, from two points, or from a graph.
Find m, then find c
Every method ends the same way: once you know the gradient m, substitute one point into y = mx + c and solve for c.
- gradient 3, through (2, 1)
- y = 3x + c
- 1 = 3 × 2 + c
- 1 = 6 + c, so c = −5
- y = 3x − 5
Check with the point: 3 × 2 − 5 = 1. It works.
The rest of this lesson and its 7 practice questions are in Plus.
Screen 1 of 4, free to read.
- 7 exam-style questions, marked as you go, each with a worked solution
- The Straight-line graphs simulation beside every question
- Anything you get wrong is saved to your flashcards