The formula d = t² + 5 t expresses a car's distance (in feet) from a stop sign, d, in terms of the number of seconds t since it started moving.
Determine the car's average speed over the interval of time from t = 4 seconds to t = 7 seconds.

The car's average speed is 16 feet per second.

Explanation:

The expression for the average speed is as follows;

Given expression of distance:

Put t= 4 s.

d(4)= 36 ft

Put t= 7 s in the given expression.

d(7)= 84 ft

Calculate the car's average speed over the interval of time from t = 4 seconds to t = 7 seconds.

A.S= 16 feet per second

Therefore, the car's average speed is 16 feet per second.

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.