The speed of a subway train is represented by the equation z=s^2+2s for all situations where 0 ≤ s ≤ 7, where z is the rate of speed in kilometers per hour and s is the time in seconds from the moment the train starts moving. In kilometers per hour, how much faster is the subway train moving after 7 seconds than it was moving after 3 seconds?
A. 4
B. 9
C. 15
D. 48
E. 63
The OA is D.
I don't have clear this PS question.
I just need to evaluate the speed equation for z(7) and z(3) and then find the difference between them? I appreciate if any expert explains it to me. Thank you so much.
A. 4
B. 9
C. 15
D. 48
E. 63
The OA is D.
I don't have clear this PS question.
I just need to evaluate the speed equation for z(7) and z(3) and then find the difference between them? I appreciate if any expert explains it to me. Thank you so much.
