Find the domain of $f$. $f ( x ) = \sqrt { x ^ { 2 } - 9 }$
A) $[ 3 , \infty )$
B) $( - \infty , - 3 ] \cup [ 3 , \infty )$
C) $( - \infty , - 3 ) \cup ( 3 , \infty )$
D) $( - 3,3 )$
E) $[ 9 , \infty )$

Question

Quizplus · Accepted Answer

The expression under the square root, $x^2 - 9$, must be non-negative. Solving $x^2 - 9 \geq 0$ gives $x \leq -3$ or $x \geq 3$. Thus, the domain is $( - \infty , - 3 ] \cup [ 3 , \infty )$.

Find the Domain Of fff f(x)=x2−9f ( x ) = \sqrt { x ^ { 2 } - 9 }f(x)=x2−9​

Find the Domain Of $f$ $f ( x ) = \sqrt { x ^ { 2 } - 9 }$