Brainlag PlusThe solution of two linear equations is where their lines cross; parallel lines have no solution.
Where the lines cross
Every point on a line fits its equation.
The one point on both lines fits both equations: that is the solution.
Parallel lines (same gradient, different intercepts) never meet, so there is no solution. If the two equations are the same line, every point is a solution.
A graph gives an estimate when the crossing is between grid lines; algebra gives the exact value.
The rest of this lesson and its 7 practice questions are in Plus.
Screen 1 of 2, 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