5. Quadratic Inequalities
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Solve the related quadratic equation, plot the solutions on a number line, and test a value from each interval.
{ x| - 1 < x < 2 }
To solve the quadratic inequality algebraically, we will follow three steps.
Substitute values
Calculate root
x=- 1 ± 3/- 2 | |
---|---|
x=- 1 + 3/- 2 | x=- 1 - 3/- 2 |
x=2/- 2 | x=- 4/- 2 |
x= - 1 | x= 2 |
The solutions of the related equation are - 1 and 2. Let's plot them on a number line. Since the original is a strict inequality, the points will be open.
Interval | Test Value | Statement | Is It Part of the Solution? |
---|---|---|---|
- 1 < x < 2 | 0 | 2 > 0 âś“ | Yes |
x > 2 | 3 | 2 ≯ 6 * | No |
We can now write the solution set and show it on a number line. { x| - 1 < x < 2 } or (- 1, 2)