A velocity at 2, 5 and 8 seconds

In physics, you are often given the position of an object as a function of time, and asked for its velocity at certain moments. The velocity is the derivative of the position. Here the position is $\displaystyle 3x^{2} - 6x + 4$, with $\displaystyle x$ in seconds. What is the velocity at 2 seconds, at 5 seconds and at 8 seconds? Press , and the . Type the function: 3, , , , , 6, , , , 4. The moves to the value of $\displaystyle x$: type 2 and press . The velocity at 2 seconds is 6.. For another moment, you do not type the function again: change only the value of $\displaystyle x$. The returns to the expression. The again puts the cursor after the value of $\displaystyle x$. A puts it on the value, and deletes it. Type 5 and press : 24.. Once more for 8 seconds: , , , , then 8 and : 42..