distance

eddy2017 said:
That is why i thought. But irslow told me I could not lose the 0. I am not blaming him I am just stating what he told me to do.
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So, at 33 when I wrote
30t -120 I didn't have to equal that to 0, right?
 
irspow said:
We got in the weeds for a bit there, I think making this problem seem more complex than it really is. The straight forward process is not that difficult.

We know both drivers went the same distance at different speeds and times. We know distance equals velocity times time. And we are given these different velocities. So:

d=vt

75(t-1)=45(t+1) distribute

75t-75=45t+45 (add 75 to both sides)

75t=45t+120 (subtract 45t from both sides)

30t=120 (divide 30 from both sides)

t=4, We can now use this t in either original distance equation to solve for d.

75(t-1)=75(4-1)=75*3=225 or

45(t+1)=45(4+1)=45*5=225

If any of that doesn’t make sense, let me know. :)
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No, everything you wrote is utter nonsense until you define your variable t. Please do not define it as we want eddy to try some more.
 
Jomo said:
eddy, start from the beginning. Do not write down any equations at all. First decide what your variable t represents. Do not move past there until you know what your variable means. If you insist I will tell you but you really should figure it out on your own. Think about where t+1 and t-1 came from. What are you adding and subtracting 1 from?
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They come from the difference in time. 1 hour late and 1 hour early but different speeds
 
eddy2017 said:
The time it took him to drive to the event.
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That could work. Then what would you call the time it took to get home from the event?

How about we use t the way you solved your equations for. Your t represents the time it would take to get to the event on time. That is why you had t-1 and t+1!!!
 
75(t-1)=45(t+1)
75t - 75 = 45t + 45
-45 t -45= -45t - 45
30 t - 120 = 0

This is how I would have this:
75(t-1)=45(t+1)
75t - 75 = 45t + 45
-45t +75 = -45t + 75
30t = 120
 
Now that you know the definition of your t, I will now say your work is fine and that t=4hours.

Can you continue from here.

I want to point out that you were amazingly lucky that your work was correct even though you did not know what your variable meant. This is unusual!
 
Jomo, just one question. Where do you think i started going wrong?.
 
I will try to get you back on track.
Let t represents the time it would take to get to the event on time.

d = 45(t+1)
d = 75(t-1)
45(t-1) = 75(t+1)
t = 4 hours.
Continue
 
I will do this problem again where t represents the time it took me to get to the event.

Going to event: d=45t
Going from the event: d = 75(t-2)

45t = 75t - 150
-45t + 150 = -45t + 150
150 = 30t
t=5 hours.

This value for t is NOT the same as your value for t!! Did I make a mistake? NO! Since I defined my variable differently from your variable I got a different value for my variable. But the distance we get using our different t's will be the same. Try it and see if I am correct.
 
Jomo said:
I will do this problem again where t represents the time it took me to get to the event.

Going to event: d=45t
Going from the event: d = 75(t-2)

45t = 75t - 150
-45t + 150 = -45t + 150
150 = 30t
t=5 hours.

This value for t is NOT the same as your value for t!! Did I make a mistake? NO! Since I defined my variable differently from your variable I got a different value for my variable. But the distance we get using our different t's will be the same. Try it and see if I am correct.
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Why going from the event?. The problem says going to the event at two different speeds. But going to. Not going from. I didn't get that?
 
eddy2017 said:
Why going from the event?. The problem says going to the event at two different speeds. But going to. Not going from. I didn't get that?
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It is good that you did not understand. I was assuming he went to the event at 45mph and returned home at 75 mph.
So forget that.
Let t represents the time it took me to get to the event at the slower speed
Going to the event at 45mph: d=45t
Going to the event at 75 mph: d = 75(t-2)

45t = 75t - 150
-45t + 150 = -45t + 150
150 = 30t
t=5 hours.
 
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