### Home > PC > Chapter 9 > Lesson 9.3.4 > Problem 9-144

9-144.

Remember our toy car with distance function

*d*(*t*) = 10*t*^{2}? Remember to label your answers with the proper units. Homework Help ✎Find the velocity of the car at 1 second, that is, find

*d*′(1).Find the velocity of the car at 3 seconds, or

*d*′(3).Find the velocity of the car at

*s*seconds for any fixed time*s*, or*d*′(*s*).

Find the slope function.

Substitute *t* = 1 into the slope function.

Substitute *t* = 3 into the slope function.

Substitute *t* = *s* into the slope function.