Need help figuring out $\frac{d}{dx}(x^2)|{x=3}$

Question

Okay, I punched this into my new calculator:

$$\frac{d}{dx}(x^2)|{x=3}$$

and it all is equal to $6$. What is this called and/or what does it do?

Answer 1

Use simple derivative formula to solve this problem.

In this case use the formula:

$\frac{d}{dx}(x^2) = 2x$

Now put $x=3$

Answer will then come to $6$

For formulas, you may refer to: Basic Differentiation Formulas