Brainlag PlusSubstitute the linear equation into the quadratic one, solve the quadratic, then find the matching values.
Substitute, then solve a quadratic
- y = x² − 3 and y = 2x
- x² − 3 = 2x
- x² − 2x − 3 = 0
- (x − 3)(x + 1) = 0, so x = 3 or x = −1
- pairs: (3, 6) and (−1, −2)
There are usually two solutions: two points where the line crosses the curve. Find y for each x using the linear equation.
The rest of this lesson and its 7 practice questions are in Plus.
Screen 1 of 3, free to read.
- 7 exam-style questions, marked as you go, each with a worked solution
- The Graphing Calculator beside every question
- Anything you get wrong is saved to your flashcards