Mathematics

Variables and Constants

Q: Which of the following statement about a variable is correct?

The value of a variable can change according to the problem or situation. 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. Therefore, option A is correct. Option B describes a constant, whose value remains fixed. Exam tip: Identify a symbol as a variable when it can take different values.

Q: How is the number 8 classified in algebra?

Constant 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. A binomial has two terms, so 8 alone is not a binomial. In exams, identify a standalone fixed number as a constant.

Q: How many variables are present in the monomial \(4xy\)?

2 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. In an algebraic term, count the distinct letters to determine the number of variables.

चर और अचर राशियाँ

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.