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 45

Find each sum or difference. 9/10 - (-4/3)

Verified step by step guidance
1
Identify the problem as a subtraction of two fractions: \(\frac{9}{10} - \left(-\frac{4}{3}\right)\).
Recognize that subtracting a negative fraction is equivalent to adding its positive counterpart, so rewrite the expression as \(\frac{9}{10} + \frac{4}{3}\).
Find the least common denominator (LCD) of the two fractions. The denominators are 10 and 3, so the LCD is the least common multiple of 10 and 3.
Convert each fraction to an equivalent fraction with the LCD as the denominator by multiplying numerator and denominator appropriately.
Add the numerators of the equivalent fractions and write the sum over the common denominator: \(\frac{\text{new numerator}}{\text{LCD}}\).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

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

Adding and Subtracting Fractions

To add or subtract fractions, they must have a common denominator. This allows you to combine the numerators directly while keeping the denominator the same. If denominators differ, find the least common denominator (LCD) first.
Recommended video:
5:56
Adding & Subtracting Functions

Subtracting Negative Numbers

Subtracting a negative number is equivalent to adding its positive counterpart. For example, a - (-b) becomes a + b. This rule simplifies expressions and helps avoid sign errors.
Recommended video:
03:18
Adding and Subtracting Complex Numbers

Finding the Least Common Denominator (LCD)

The LCD is the smallest number that both denominators divide into evenly. It is used to rewrite fractions with different denominators into equivalent fractions with the same denominator, enabling addition or subtraction.
Recommended video:
Guided course
03:42
Rationalizing Denominators Using Conjugates