Math is not my subject Need help !!!!!!

K

kcjordan

New member
Joined
Jul 23, 2005
Messages
8
:cry: This old timer needs alot of help with math if anyone can help please log into my Aim or my yahoo messager

I have a quiz that I know that I really need help on the preview I have
 
You may wish to post a specific problem with which you are struggling.
 
This 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=
 
kcjordan said:
This is one of the problems
Code: 
  6     3
---- + --
3x-1   4x
Click to expand...
Are we adding and simplifying?

First thing is a common denominator.

How shall we go about that?
 
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)]
 
kcjordan said:
This 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=
Click to expand...
I'm confused; where does 6 / (3x - 1) + 3 /(4x) come from?

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?
 
Confusion comes from "last edited", above. It WAS there.
 
Denis said:
KC, WHAT question?
Can you post whatever it is again...
Click to expand...

The word question is one I neded help with....


also this problem

x+3 -x
underline
x+2 - x-2
 
Denis said:
KC, WHAT question?
Can you post whatever it is again...
Click to expand...

one of the problems was 24times 21
120 times 63 this is a fraction times a fraction


24/120 x 21/63
 
Denis said:
KC, WHAT question? Can you post whatever it is again...
Click to expand...
kcjordan said:
The word question is one I neded help with.
Click to expand...
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:
also this problem
x+3 -x
underline
x+2 - x-2
Click to expand...
:shock:

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
...which is just "zero divided by zero", which arguably has no meaning.

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.
 
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)
 
You must log in or register to reply here.
Top