The Harmonic series 1 + 1/2 + 1/3 + 1/4 + ... is related to rational expressions. It's a famous series that diverges, which means its sum grows without bound. It seems like the fractions get smaller and smaller and should add up to a finite number, but they just don't!

Do exercises to learn how to add rational expressions.

A common denominator is a common multiple of the denominators of two or more fractions

The least common denominator (LCD) is the smallest expression that can serve as a common denominator for two or more fractions, whether the denominators are numerical or algebraic

Simplifying a fraction involves reducing it to its lowest terms by dividing both the numerator and the denominator by their greatest common factor