Skip to main content
Ch. R - Review of Basic Concepts
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 1, Problem 147

Evaluate each expression for x = -4 and y = 2. 2|y| - 3|x| / |xy|

Verified step by step guidance
1
First, substitute the given values into the expression: replace \( x \) with \( -4 \) and \( y \) with \( 2 \) in the expression \( 2|y| - \frac{3|x|}{|xy|} \).
Calculate the absolute values: find \( |y| \), \( |x| \), and \( |xy| \). Remember that the absolute value of a number is its distance from zero, so it is always non-negative.
Rewrite the expression with the absolute values calculated: \( 2|y| - \frac{3|x|}{|xy|} \) becomes \( 2 \times |2| - \frac{3 \times | -4 |}{|(-4)(2)|} \).
Perform the multiplications and division inside the expression step-by-step: multiply \( 2 \times |2| \), multiply \( 3 \times | -4 | \), and then divide by \( |(-4)(2)| \).
Finally, subtract the fraction from the product \( 2|y| \) to get the simplified expression value.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1m
Was this helpful?

Key Concepts

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

Absolute Value

The absolute value of a number is its distance from zero on the number line, always expressed as a non-negative value. For example, |x| equals x if x is positive or zero, and -x if x is negative. This concept is essential for correctly evaluating expressions involving absolute values.
Recommended video:
7:12
Parabolas as Conic Sections Example 1

Substitution of Variables

Substitution involves replacing variables in an expression with given numerical values. Here, x and y are replaced with -4 and 2 respectively, allowing the expression to be evaluated numerically. Accurate substitution is crucial for solving algebraic expressions.
Recommended video:
Guided course
5:48
Solving Systems of Equations - Substitution

Order of Operations

The order of operations dictates the sequence in which parts of an expression are evaluated, typically parentheses, exponents, multiplication/division, and addition/subtraction (PEMDAS). Applying this correctly ensures the expression is simplified accurately, especially when fractions and absolute values are involved.
Recommended video:
Guided course
8:38
Performing Row Operations on Matrices