To find \((f+g)(-9)\), we need to first determine the expressions for \(f(x)\) and \(g(x)\). Then, we add these two expressions to get \((f+g)(x)\). Finally, we substitute \(-9\) into this new expression to find the result.
Step 1: Define the Functions
We have the functions defined as:
\[
f(x) = 2x + 5
\]
\[
g(x) = x + 1
\]
Step 2: Find the Sum of the Functions
To find \((f + g)(x)\), we add the two functions:
\[
(f + g)(x) = f(x) + g(x) = (2x + 5) + (x + 1) = 3x + 6
\]
Step 3: Evaluate at \(x = -9\)
Now, we substitute \(x = -9\) into the sum:
\[
(f + g)(-9) = 3(-9) + 6 = -27 + 6 = -21
\]