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This topic plots and interprets straight-line graphs, finds the gradient and y-intercept, and uses y = mx + c to write and recognise the equation of a line. It's a core topic in GCSE and iGCSE Maths with Edexcel and the other major boards. This free interactive eClassroom course walks through each step with worked examples and instant-feedback questions, so you can practise until it's secure.
How you do it
Write the equation as y equals mx plus c, where m is the gradient and c is where it crosses the y-axis. Plot the intercept, then use the gradient as a step: along one, up m. Parallel lines share a gradient; perpendicular gradients multiply to give minus 1.
Before you start
The groundwork here is coordinates and substitution. It sets up simultaneous equations and gradients. It is Foundation and Higher tier material at GCSE and iGCSE.
What you learn
A linear graph is a straight line with equation y = mx + c, where m is the gradient (steepness) and c is the y-intercept (where it crosses the y-axis). These two numbers describe the line completely. In y = mx + c, the gradient m is the number in front of x and the y-intercept c is the constant — the value of y where the line crosses the y-axis. Pick two points on the line and divide the rise by the run. Once you know the gradient m and the y-intercept c, the equation is simply y = mx + c. The course works through y = mx + c, gradient from two points and the equation of a line. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
Linear Graphs is a Algebra topic in the GCSE syllabus, covered here at Foundation tier. You work through 3 concepts and 2 worked examples, testing yourself at 3 points. Nearby topics in the same strand are Quadratic Equations, Quadratic Inequalities, Rearranging Formulae and Sequences. For unlimited practice, the Algebra revision engine builds new questions on demand and records your accuracy.
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