To find the initial value of the temperature equation \( T(x) = 2x + 10 \) when \( x \) equals the number of hours after noon, we need to evaluate the equation at \( x = 0 \) (which represents noon).
Substituting \( x = 0 \) into the equation:
\[ T(0) = 2(0) + 10 = 0 + 10 = 10 \]
Therefore, the initial value of the temperature at noon is 10°C.
So, the correct response is:
10°C