Algebra · Straight-line graphs
Chapter 1 · 3
The idea
Finding the equation of a line
How gradient + one point pins down a unique line, why c comes from substituting the point, and why disguised forms like 2y = 6x + 4 must be rearranged before reading anything off.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Algebra · Straight-line graphs
Finding the equation of a line
How gradient + one point pins down a unique line, why c comes from substituting the point, and why disguised forms like 2y = 6x + 4 must be rearranged before reading anything off.
Why it works
Two facts pin a line
Why does "find the equation of the line" always hand you exactly two pieces of information? Because one is never enough: know only the gradient and every parallel line fits; know only a point and every line through it fits — an infinite fan either way. Two facts — a gradient and a point, or two points — cut the candidates down to exactly one line, and finding its equation means recovering from whichever two facts you're given.Keep reading — free
The rest of the explanation, plus 2 worked examples you step through move by move.
Start freeTakes a minute — no card.