The rule for rewriting an absolute value equation without absolute value bars can be extended to equations with two sets of absolute value bars: If u and v represent algebraic expressions, then |u| = |v| is equivalent to u = v or u = - v. Use this to solve the equations in Exercises 77–84. |3x - 1| = |x + 5|
Table of contents
- 0. Review of Algebra4h 18m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations1h 43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 5m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 22m
- 10. Combinatorics & Probability1h 45m
1. Equations & Inequalities
Linear Equations
Problem 69
Textbook Question
In Exercises 61–76, solve each absolute value equation or indicate that the equation has no solution. 7|5x| + 2 = 16
Verified step by step guidance1
Start by isolating the absolute value expression. Subtract 2 from both sides of the equation: \$7|5x| + 2 - 2 = 16 - 2\(, which simplifies to \)7|5x| = 14$.
Next, divide both sides of the equation by 7 to solve for \(|5x|\): \(\frac{7|5x|}{7} = \frac{14}{7}\), giving \(|5x| = 2\).
Recall that the absolute value equation \(|A| = B\) means \(A = B\) or \(A = -B\). So, set up two equations: \$5x = 2\( and \)5x = -2$.
Solve each equation for \(x\) by dividing both sides by 5: \(x = \frac{2}{5}\) and \(x = \frac{-2}{5}\).
These two values are the solutions to the original equation. You can check each by substituting back into the original equation to verify correctness.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Absolute Value Definition
The absolute value of a number represents its distance from zero on the number line, always yielding a non-negative result. For any real number x, |x| equals x if x is positive or zero, and -x if x is negative. Understanding this helps in setting up equations when absolute values are involved.
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Solving Absolute Value Equations
To solve an equation involving absolute values, isolate the absolute value expression first. Then, split the equation into two cases: one where the expression inside the absolute value equals the positive value, and one where it equals the negative value. Solve both cases separately to find all possible solutions.
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Checking for Extraneous Solutions
After solving absolute value equations, it is important to verify each solution by substituting back into the original equation. Some solutions may not satisfy the original equation due to the nature of absolute values, so checking prevents including invalid answers.
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