Question #N388
The function $f(x)$ is defined by $f(x) = \sqrt{x} - 4$. For what value of $x$ does $f(x) = 9$?
A. 13
B. 81
C. 169
D. 289
Correct Answer is: C
To solve for $x$, we set the function equal to 9: $\sqrt{x} - 4 = 9$. Adding 4 to both sides gives us $\sqrt{x} = 13$. Squaring both sides, we get $x = 13^2$, or $x = 169$.