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

kcjordan

New member
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

tkhunny

Moderator
Staff member
You may wish to post a specific problem with which you are struggling.

kcjordan

New member
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=

tkhunny

Moderator
Staff member
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?

kcjordan

New member
yes, we have to find the the lower number than simplify

kcjordan

New member
tkhunny said:
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

tkhunny

Moderator
Staff member
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)]

Denis

Senior Member
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=
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?

tkhunny

Moderator
Staff member
Confusion comes from "last edited", above. It WAS there.

kcjordan

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

Denis

Senior Member
KC, WHAT question?
Can you post whatever it is again...

kcjordan

New member
Denis said:
KC, WHAT question?
Can you post whatever it is again...
The word question is one I neded help with....

also this problem

x+3 -x
underline
x+2 - x-2

kcjordan

New member
Denis said:
KC, WHAT question?
Can you post whatever it is again...
one of the problems was 24times 21
120 times 63 this is a fraction times a fraction

24/120 x 21/63

stapel

Super Moderator
Staff member
Denis said:
KC, WHAT question? Can you post whatever it is again...
kcjordan said:
The word question is one I neded help with.
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
: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.

Eliz.

kcjordan

New member
ok here we go again!

problem 1

6+3=
3x-1 4x

problem 2

x+3minus x =
x+2 x-2

Denis

Senior Member
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)