- Thread starter kcjordan
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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=

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Are we adding and simplifying?kcjordan said:This is one of the problems

Code:`6 3 ---- + -- 3x-1 4x`

First thing is a common denominator.

How shall we go about that?

tkhunny said:Are we adding and simplifying?kcjordan said:This is one of the problems

Code:`6 3 ---- + -- 3x-1 4x`

First thing is a common denominator.

How shall we go about that?

would it be 9 over 2

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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:

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=

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?

Ok Now I am confused what was the answer for the word Question?tkhunny said:Confusion comes from "last edited", above. It WAS there.

The word question is one I neded help with....Denis said:KC, WHAT question?

Can you post whatever it is again...

also this problem

x+3 -x

underline

x+2 - x-2

one of the problems wasDenis said:KC, WHAT question?

Can you post whatever it is again...

120 times 63 this is a fraction times a fraction

24/120 x 21/63

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Denis said:KC, WHAT question? Can you post whatever it is again...

Um...kcjordan said:The word question is one I neded help with.

:shock:kcjordan said:also this problem

x+3 -x

underline

x+2 - x-2

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 - 2
```

Please 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.

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)