Mathematics
Variables and Constants
In this Class 9 Mathematics topic from the Common Questions chapter, students learn how variables and constants work in algebra. They identify quantities that can change, such as x or y, and fixed values such as 5 or 12. The topic explains how these symbols are used in algebraic expressions, how substituting values changes an expression’s result, and how to distinguish a variable from a constant while reading and forming simple mathematical statements.
Topic overviewटॉपिक का परिचय
Concept revisionअवधारणाओं का पुनरावर्तन
Which of the following statement about a variable is correct?
A variable is a symbol representing a number or quantity whose value may change according to the problem or situation. For example, in \(x+3=8\), \(x=5\), but \(x\) may have a different value in another problem.
How is the number 8 classified in algebra?
The number 8 has a fixed value and contains no variable, so it is a constant. A variable, such as x, can take different values.
How many variables are present in the monomial \(4xy\)?
In \(4xy\), \(x\) and \(y\) are two distinct variables, so the number of variables is 2. The number 4 is a constant coefficient, not a variable.