Solving Absolute Value Equations
The equation in the next example involves absolute value.
Example 1
Solving an absolute value equation by factoring
Solve | x2 - 2x - 16
| = 8.
Solution
First write an equivalent compound equation without absolute value:
x2 - 2x - 16 = 8 |
or |
x2 - 2x - 16 = -8 |
x2 - 2x - 24 = 0 |
or |
x2 - 2x - 8 = 0 |
(x - 6)(x + 4) = 0 |
or |
(x - 4)(x + 2) = 0 |
x - 6 = 0 |
or |
x + 4 = 0 |
or |
x - 4 = 0 |
or |
x + 2 = 0 |
x = 6 |
or |
x = -4 |
or |
x = 4 |
or |
x = -2 |
The solution set is {-2, -4, 4, 6}. Check each solution.
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