Question

HALP MEH

http://assets.openstudy.com/updates/attachments/543c7244e4b0f0e39fb94ce2-math_sucks123-1413248025589-openstudyhelp.png

Walk me through this plz?
@phi

Answer 1

can you answer the first question about x-intercept for car 1?

Answer 2

I know its 70, sorry theres a REALLY loud landscaping team going through our neighborhood right now and it is nigh impossible to think!

Answer 3

yes, 70 and it is always good to include the units
70 minutes.
and what does 70 minutes represent?

Answer 4

the y value is 0 (km from destination)
so after 70 minutes, car 1 is at its destination

Answer 5

oh! I get it! so for car 2 the y value is also 0, but I am confused because the graph does not seem to reach the destination!

Answer 6

the graph does not show car 2 every reaching its destination. But that's ok, they don't ask about that.

to review, for question A, the x-intercept represents how long it takes car 1 to reach its destination, which is 70 minutes

Answer 7

what about Q B?

Answer 8

oh! ok now I get it, question b I am guessing is the distance travelled?

Answer 9

the y axis is "distance from the destination"
so I would say, "how far car 2 has to go to reach its destination, namely 70 km"

Answer 10

I see I see, so the y intercept is distance car 2 must travel before reaching destination

Answer 11

yes, and maybe add, starting at time 0

Answer 12

but wait, car 2 does not appear to have a destination

Answer 13

the domain are the "legal x values"
It is not clear if time before 0 is allowed (the graph shows a line, but the table starts at zero)
I would go with x >=0

Answer 14

the graph for car 2 shows that it is getting closer to its destination, but it has not reached it by time 80 minutes (and for all we know it never reaches the x-axis). Car 2 is slowing down (flat tire?)

Answer 15

what would be the y intercept for car 2 then?

Answer 16

the y-intercept is where the line meets the y-axis (on the left side where x=0)

Answer 17

so 70?

Answer 18

yes. the y-intercept represents the distance that car 2 has to go to reach its destination at the start (at time 0)

Answer 19

I think I have the domain of car 1 and 2, but car 2 is iffy, domain of car 1 is (0,70)? domain of car 2 appears to be infinite...

Answer 20

@phi

Answer 21

yes,
but for car1 I would use [0, 70] because both 0 and 70 are included.
for car 2 [0, infinity)
(as a guess)

Answer 22

okay, what about part d? What is the average rate of change from x = 30 to x = 40 for the function representing the motion for car 2? What does the value of this average rate of change represent?

Answer 23

figure out "change in y" divided by "change in x"

Answer 24

so 6.98488/10=0.698488?

Answer 25

yes. or about 0.7 km/minute
that is the average speed

Answer 26

thanks! how do I medal? first time here