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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 78

The temperatures on the surface of Mars in degrees Celsius approximately satisfy the inequality C+846 |C + 84 | ≤ 6. What range of temperatures corresponds to this inequality?

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1
Recognize that the inequality involves an absolute value: \(|C + 84| \leq 6\). This means the expression inside the absolute value, \(C + 84\), is at most 6 units away from 0 on the number line.
Rewrite the absolute value inequality \(|C + 84| \leq 6\) as a compound inequality without the absolute value: \(-6 \leq C + 84 \leq 6\).
Isolate the variable \(C\) by subtracting 84 from all parts of the inequality: \(-6 - 84 \leq C + 84 - 84 \leq 6 - 84\).
Simplify the inequality to get the range for \(C\): \(-90 \leq C \leq -78\).
Interpret the result: the temperatures \(C\) on the surface of Mars lie between \(-90\) degrees Celsius and \(-78\) degrees Celsius, inclusive.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Absolute Value Inequality

An absolute value inequality like |x| ≤ a means the distance of x from zero is at most a. It can be rewritten as a compound inequality: -a ≤ x ≤ a. This helps in finding the range of values that satisfy the inequality.
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Translating Absolute Value Inequalities

When the absolute value involves an expression, such as |C + 84| ≤ 6, rewrite it as -6 ≤ C + 84 ≤ 6. This isolates the variable by breaking the inequality into two parts, making it easier to solve for C.
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Solving Compound Inequalities

To solve -6 ≤ C + 84 ≤ 6, subtract 84 from all parts to isolate C, resulting in -90 ≤ C ≤ -78. This gives the range of temperatures that satisfy the original inequality.
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