Question

Given f, of, x, equals, minus, x, squared, plus, 5, x, minus, 18f(x)=−x
2
+5x−18, find f, of, minus, 3f(−3)

Answer 1

To find \( f(-3) \) for the function \( f(x) = -x^2 + 5x - 18 \), we need to substitute \( -3 \) into the function:

\[
f(-3) = -(-3)^2 + 5(-3) - 18
\]

Calculating this step by step:

1. Calculate \( (-3)^2 \):
\[
(-3)^2 = 9
\]

2. Substitute into the function:
\[
f(-3) = -9 + 5(-3) - 18
\]

3. Calculate \( 5(-3) \):
\[
5(-3) = -15
\]

4. Substitute back into the function:
\[
f(-3) = -9 - 15 - 18
\]

5. Now perform the addition/subtraction:
\[
-9 - 15 = -24
\]
\[
-24 - 18 = -42
\]

Thus, we find that:
\[
f(-3) = -42
\]

The final answer is:
\[
f(-3) = -42
\]