evaluate f(x) when x = 9

Answer : C
i.e. f(x) =12 when x = 9
Explanation :
Since we have given that
[tex]f(x) =6x^2+2\text{ if} -6<x<9\text{ and } f(x) = 12 \text{ if }9\leq x\leq 13[/tex]
x=9 lies in the interval [9,13]
so f(x) will be 12 for x=9
in another interval i.e (-6,9)
x can't be 9 as it is an open interval which does not include 9 .
so we'll go for f(x)=12 when x=9.
when x = 9, use the bottom equation because 9 ≤ 9 < 13
f(x) = 12
f(9) = 12 there is no "x" to replace with 9 so the value doen't change.
Answer: C