Question

Given f, of, x, equals, minus, x, squared, plus, x, plus, 20f(x)=−x
2
+x+20, find f, of, minus, 3f(−3)

Answer 1

To find \( f(-3) \) given the function \( f(x) = -x^2 + x + 20 \), we will substitute \(-3\) into the function.

1. First, substitute \(-3\) for \(x\) in the function:
\[
f(-3) = -(-3)^2 + (-3) + 20
\]

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

3. Substitute this value back into the equation:
\[
f(-3) = -9 - 3 + 20
\]

4. Simplify:
\[
f(-3) = -12 + 20 = 8
\]

Therefore, \( f(-3) = 8 \).

Thus, the final answer is:
\[
f(-3) = 8
\]