MathematicsClass 7Simple Equations
Concept of a Variable
Understanding how letters or symbols represent unknown quantities in mathematical expressions.
Class 7 · MathematicsCBSE & ICSE SOF IMO
Definition
A variable is a quantity that can change or vary and does not have a fixed value. In mathematics, it is typically represented by English alphabets like x, y, z, or m. Variables allow us to express general mathematical statements and relationships where exact numbers are initially unknown.
Worked examples
1
If Raju has x apples and eats 2, the number of remaining apples is represented by the algebraic expression x - 2.
2
The perimeter of a square with side length s is expressed as 4s, where s is the variable.
3
In the equation 3y + 5 = 14, y is the variable whose value needs to be determined.
Common mistakes
- • Confusing a variable with a fixed constant or a specific number.
- • Assuming that the same letter always represents the same value across completely different word problems.