Final answer:
f(-1) for the function f(x) = 20x² - 18 - 25, is f(-1) = -23.
Step-by-step explanation:
To find f(-1) for the given function, f(x) = 20x² - 18 - 25, substitute x with -1 in the function:
f(-1) = 20(-1)² - 18 - 25
First, calculate (-1)²:
-1 ² = 1
Next, multiply this value by 20:
20 × 1 = 20
Now, subtract 18 and then 25 from this result:
20 - 18 = 2
2 - 25 = -23
Therefore, f(-1) = -23.