I asked this before but I don't understand part C. Could you explain it in easier terms?

Question

The velocity of a subatomic particle moving through space can be modeled by

v(t)=0.1t^2 −2t +0.2

for t≥0 where t is time in seconds and v is velocity in m/s.
Find the following:

a) (a) The time(s) t at which the particle is not moving:
......... and .........

b)The interval(s) over which the particle is moving forward: (Remember to write union as U and infinite as INF) ..................

c)The interval(s) over which the particle is moving backwards: (Remember to write union as U and infinite as INF) ..................

Thanks!

I know A is The time(s) t at which the particle is not moving: 0.10 and 19.90

I know B is [0, 0.10) U(19.90, INF)
But:
I thought C would be (-0.10, 19.90) but it says wrong..
Thank you

Answer 1

The equation is only applicable at positive t.
-0.10 is not allowed
0.10 < t < 19.90 is when it is in reverse

Answer 2

Anonymous, how would I enter that in the boxes....see above image

thanks