When you compute $(-3)^2$, think about whether the result should be positive or negative.

After substitution, calculate $2(-3)^2$, then $-5(-3)$, and then add those results with $4$.

Once you have the three numerical terms, add them step by step, watching the signs carefully.

In the first expression line, type f(x) = 2x^2 - 5x + 4 so Desmos defines the function.

In a new line, type f(-3) and look at the numeric output that Desmos shows; that number is the value of $f(-3)$.

We are given the function

and asked to find $f(-3)$.

Substitute $x = -3$ into the function (always use parentheses with negatives):

First, square $-3$:

Now multiply:

• $2(-3)^2 = 2\cdot 9 = 18$
• $-5(-3) = 15$

So the expression becomes

Now add the three numbers:

• $18 + 15 = 33$
• $33 + 4 = 37$

So the value of $f(-3)$ is 37.