Find all numbers that are not in the domain of the function. Then give the domain using set notation.
-$f(x)=\frac{12}{x^{2}+7 x-18}$

A) $-9,2 ;\{x \mid x \neq-9,2\}$

B) 0 ; $\{x \mid x \neq 0\}$

C) $-2,9 ;\{x \mid x \neq-2,9\}$

D) $0,-9 ;\{x \mid x \neq 0,-9\}$

Question

Find all numbers that are not in the domain of the function. Then give the domain using set notation.
-$f(x)=\frac{12}{x^{2}+7 x-18}$

A) $-9,2 ;\{x \mid x \neq-9,2\}$

B) 0 ; $\{x \mid x \neq 0\}$

C) $-2,9 ;\{x \mid x \neq-2,9\}$

D) $0,-9 ;\{x \mid x \neq 0,-9\}$

Quizplus · Accepted Answer

The function $f(x)=\frac{12}{x^{2}+7x-18}$ is undefined when the denominator is zero. Factoring the denominator gives $x^{2}+7x-18=(x+9)(x-2)$, so the function is undefined at $x=-9$ and $x=2$. Thus, the domain is $\{x \mid x \neq-9,2\}$.

Find All Numbers That Are Not in the Domain of the Function