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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 2, Problem 12

Solve each equation. |7 - 3x| = 3

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1
Recognize that the equation involves an absolute value: \(|7 - 3x| = 3\). Recall that \(|A| = B\) means \(A = B\) or \(A = -B\) when \(B \geq 0\).
Set up two separate equations based on the definition of absolute value: \$7 - 3x = 3\( and \)7 - 3x = -3$.
Solve the first equation \$7 - 3x = 3\( by isolating \)x\(: subtract 7 from both sides to get \)-3x = 3 - 7\(, then divide both sides by \)-3$.
Solve the second equation \$7 - 3x = -3\( similarly: subtract 7 from both sides to get \)-3x = -3 - 7\(, then divide both sides by \)-3$.
Write the two solutions for \(x\) obtained from the two equations as the complete solution set to the original absolute value equation.

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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 as a non-negative value. For an expression |A| = B, where B ≥ 0, the equation splits into two cases: A = B or A = -B. Understanding this is essential to solving equations involving absolute values.
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Solving Linear Equations

Once the absolute value equation is split into two linear equations, each must be solved separately. This involves isolating the variable by performing inverse operations such as addition, subtraction, multiplication, or division to find the value of x.
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Checking Solutions in Absolute Value Equations

After finding potential solutions, it is important to verify them by substituting back into the original absolute value equation. This ensures that extraneous solutions, which can arise from the splitting process, are identified and discarded if they do not satisfy the original equation.
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Related Practice
Textbook Question

Use Choices A–D to answer each question. A. 3x2 - 17x - 6 = 0 B. (2x + 5)2 = 7 C. x2 + x = 12 D. (3x - 1)(x - 7) = 0 Only one of the equations is set up so that the values of a, b, and c can be determined immediately. Which one is it? Solve it.

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Textbook Question

Use the following facts. If x represents an integer, then x+1 represents the next consecutive integer. If x represents an even integer, then x+2 represents the next consecutive even integer. If x represents an odd integer, then x+2 represents the next consecutive odd integer. Find two consecutive even integers whose product is 224.

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Textbook Question

Use Choices A–D to answer each question. A. 3x2 - 17x - 6 = 0 B. (2x + 5)2 = 7 C. x2 + x = 12 D. (3x - 1)(x - 7) = 0 Only one of the equations does not require Step 1 of the method for completing the square described in this section. Which one is it? Solve it.

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