F(x)=2x^2-5x-20
find f(-9)

The output when x = -9 is f(x) = 187.

Step-by-step explanation:

We are given a function and asked to find the output of that function.

Our standard function is in the form of a quadratic equation.

Let's check for a change in the presentation of the first value in the equation.

We see that x becomes -9. We also know that from conventional algebra, we need to make this change throughout the entire equation. Therefore, since we changed the x in f(x), we need to change it in 2x² - 5x - 20 as well.

Now, it's time to simplify this function. Let's first simplify the first term of the function: .

Let's follow PEMDAS in order to simplify the term.

P - Parentheses

E - Exponents

M - Multiplication

D - Division

A - Addition

S - Subtraction

When using this acronym, make sure that all operations are performed left to right.

We see that -9 is raised to the power of 2, so we square -9. Otherwise, we carry out the following operation.

Then, we see that 2 is multiplied into this value. Therefore, we multiply 81 by 2.

Now, we need to subtract the product of 5 and -9.

Finally, we subtract 20 from this value.

Therefore, the value of f(-9) is 187.