Solve |x + 1| = 12
Absolute value equation, worked out line by line the way a teacher would write it.
Answer
| Solutions | x = −13, x = 11 |
Step-by-step solution
7 steps-
1 Given\left|{x + 1}\right| = 12
Solve for x.
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2 Split into two cases: the expression inside the bars is either 12 or -12
|u| is the distance of u from 0. A distance of 12 can be on either side of 0, so the inside is 12 or the opposite of 12, and each case is solved as its own equation.
x + 1 = 12\quad \text{or} \quad x + 1 = -12 -
3 Case 1x + 1 = 12
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4 Subtract 1 from both sides
An equation stays true as long as you do the same thing to both sides, like adding the same weight to both pans of a balance. Adding or subtracting the same amount on both sides moves a term to the other side, where it appears with the opposite sign.
x = 11Move the constant terms to the right.
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5 Case 2x + 1 = -12
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6 Subtract 1 from both sidesx = -13
Move the constant terms to the right.
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7 Check\begin{aligned}x = -13:\quad 12 = 12\quad\checkmark\\ x = 11:\quad 12 = 12\quad\checkmark\end{aligned}
Substituting each solution back makes both sides equal.
Check by substitution
| x | Left side | Right side | |
|---|---|---|---|
| −13 | 12 | 12 | ✓ |
| 11 | 12 | 12 | ✓ |
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