Find the domain of the algebraic expression (x^2 - 9)/(x - 3).

Find the domain of the algebraic expression $\frac{x ^{2} - 9}{x - 3}$ .

medium 2 marks Class 7 · Mathematics · Algebraic Expressions

Answer

All real numbers except 3

The correct answer is All real numbers except 3 — The domain is all real numbers except $x = 3$ .

Identify the values of $x$ that make the denominator zero; set $x - 3 = 0 \to x = 3$ .
Since division by zero is undefined, $x = 3$ must be excluded from the domain.
The domain is all real numbers except $x = 3$ .

Common mistake: Simplifying the fraction first and then claiming all real numbers

Concept tested: Domain of rational expression