Math is not my subject Need help !!!!!!
- Thread starter kcjordan
- Start date
This old timer needs alot of help with math if anyone can help please log into my Aim or my yahoo messagerThis is one of the problems
Traveling time. A driver drives the first leg (400 km) of a trip at X km/hr and decreases his speed by 15 km/hr for the second leg (20 km).
Write a rational expression for his total trip time.
Evaluate this expression for x=60 and x=90
for x=60,time =
forx=90,times=
Traveling time. A driver drives the first leg (400 km) of a trip at X km/hr and decreases his speed by 15 km/hr for the second leg (20 km).
Write a rational expression for his total trip time.
Evaluate this expression for x=60 and x=90
for x=60,time =
forx=90,times=
- Joined
- Apr 12, 2005
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- 11,339
6/(3x-1) + 3/(4x)
Denominators....... (3x-1) and (4x)
Least Common Denominator (3x-1)*(4x)
Multiply each term by an appropriate factor (=1) to make it up to the common denominator.
[6/(3x-1)]*(4x/4x) + [3/(4x)]*[(3x-1)(3x-1)]
Expand and simplify NUMERATORS separately.
6*4x/[(3x-1)*(4x)] + 3(3x-1)/[(3x-1)*(4x)]
Combine over the common denominator
[6*4x + 3(3x-1)]/[(3x-1)*(4x)]
[24x + 9x - 3]/[(3x-1)*(4x)]
[33x - 3]/[(3x-1)*(4x)]
Factor if possible
3*[11x - 1]/[(3x-1)*(4x)]
Denominators....... (3x-1) and (4x)
Least Common Denominator (3x-1)*(4x)
Multiply each term by an appropriate factor (=1) to make it up to the common denominator.
[6/(3x-1)]*(4x/4x) + [3/(4x)]*[(3x-1)(3x-1)]
Expand and simplify NUMERATORS separately.
6*4x/[(3x-1)*(4x)] + 3(3x-1)/[(3x-1)*(4x)]
Combine over the common denominator
[6*4x + 3(3x-1)]/[(3x-1)*(4x)]
[24x + 9x - 3]/[(3x-1)*(4x)]
[33x - 3]/[(3x-1)*(4x)]
Factor if possible
3*[11x - 1]/[(3x-1)*(4x)]
I'm confused; where does 6 / (3x - 1) + 3 /(4x) come from?kcjordan said:
Above problem (speed = distance / time):
time for 400km : 400 / x
time for 20km : 20 / (x - 15)
total time:
400 / x + 20 / (x - 15)
= [400(x - 15) + 20x] / [x(x - 15)]
= 400x - 6000 + 20x) / [x(x - 15)]
= (420x - 6000) / [x(x - 15)]
= 60(7x - 100) / [x(x - 15)]
no?
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- Feb 4, 2004
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- 16,583
Denis said:
Um... most questions contain at least a few words. Would you please post the exact and complete text of the question? Thank you.kcjordan said:
:shock:kcjordan said:
1) Please post new questions as new threads, not as replies to old questions.
2) Please format your question so as to be intellible to others.
3) Please include the complete instructions to all questions.
This can't be a "solve" problem, as you have posted, because it doesn't have an "equals" sign in it, and therefore there is nothing to "solve". What you have posted is:
Code:
x + 3 - x
-------------
x + 2 - x - 2Please reply to the previous tutor's request, and please post this new exercise in a clearly-formatted new thread, complete with instructions. Thank you for your consideration.
Eliz.
boy oh boy, KC...
can you find someone in Texas that knows how to post properly
to show you how; it's something that's hard for us to do here...
I can try a couple of examples:
2 divided by x + 1 : 2 / (x + 1)
x + 2 divided by 6 then 7 is added: (x + 2) / 6 + 7
x + 2 divided by 6 + 7 : (x + 2) / (6 + 7)
can you find someone in Texas that knows how to post properly
to show you how; it's something that's hard for us to do here...
I can try a couple of examples:
2 divided by x + 1 : 2 / (x + 1)
x + 2 divided by 6 then 7 is added: (x + 2) / 6 + 7
x + 2 divided by 6 + 7 : (x + 2) / (6 + 7)