GCSE Maths: Straight-Line Graphs
Master GCSE Maths straight-line graphs — gradient, y-intercept, y = mx + c, perpendicular and parallel lines. AQA, Edexcel, OCR and Eduqas.
AlgebraFoundation & HigherAQA · Edexcel · OCR · Eduqas
What you need to know
The concepts examiners test on straight-line graphs, and what each one is really asking.
Gradient of a straight line
y = mx + c
Finding the equation of a line
Parallel and perpendicular lines
Midpoint and distance between two points
Where marks get lost
The exam technique that separates a correct method from a correct answer.
- Gradient = rise ÷ run = (y₂−y₁)/(x₂−x₁)
- Parallel lines have the same gradient
- Perpendicular lines: gradients multiply to −1
Straight-Line Graphs questions students ask
How do I find the equation of a straight line?
Find the gradient m using two points, then substitute one point into y = mx + c to find c.
How do I find a perpendicular gradient?
If the original gradient is m, the perpendicular gradient is −1/m (the negative reciprocal).