Algebra 1 / Unit 2: Solving Equations
2.7 Absolute Value Equations
Notes
The absolute value $|x|$ is a number's distance from 0, so it is never negative.
- $|x| = 5$ means $x = 5$ or $x = -5$.
- Isolate the absolute value first, then split: $|2x - 1| = 7 \Rightarrow 2x - 1 = 7$ or $2x - 1 = -7$, so $x = 4$ or $x = -3$.
- If an absolute value equals a negative number, there is no solution.
Practice
Solve $|x + 3| = 8$.
$x + 3 = 8$ or $x + 3 = -8$.
Solve $|4y| - 2 = 10$.
$|4y| = 12$, so $4y = \pm 12$.
How many solutions does $|x - 6| = -2$ have?
Absolute value can't be negative.
Ready for more? Take the Unit 2 test.