Algebraic expression
- CBSE · NCERT Class 7 Part 1, Ch 4 Expressions using Letter-Numbers
An algebraic expression is a mix of numbers and letters joined by signs like + and ×, such as 3x + 5, with no equals sign.
An expression is a phrase in maths, not a full sentence. It uses variables and numbers, but it makes no claim. 3x + 5 is an expression. 3x + 5 = 20 is an equation, because the equals sign states a fact.
The parts joined by + or - are its terms. In 4x² - 7x + 2 there are three terms: 4x², -7x and 2. Terms with the same letters and powers are like terms, and only they can be added together.
A small example
Simplify 5a + 3b - 2a + b. Group the like terms: 5a - 2a = 3a, and 3b + b = 4b. The answer is 3a + 4b. You cannot join 3a and 4b, because they are unlike terms.
An expression also takes a value once you know the letters. If a = 2 and b = 1, then 3a + 4b = 6 + 4 = 10.
Why it matters later
Class 10 Chapter 2 studies polynomials, which are a tidy kind of algebraic expression. A quadratic polynomial such as x² - 5x + 6 is one. Finding its zeroes, or checking a factorisation, uses the same skills: spotting terms, joining like terms and substituting values.
Sources
Facts last checked against these sources on 30 September 2026.
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