Math Help

[AlexShymkiw]

Okay all you math whizs out there, I need your help. I'm upgrading Math 11 for post-secondary and I haven't done the course for about two years. My tutor is away at the moment. I'm a little bit rusty so I need your help in solving this review question to prepare for the Chapter test.

-5/3X + 7/3 = -5

The answer is 22/5

Can anyone outline for me what steps I need to take to identify what X is?

[dan_the_man]

The answer is wrong.

It's 5 over 22.

-5/3X + 7/3 = -5

-5(3) + 7(3X) = -5(3)(3X)

-15 + 21X = -45X

-15 = -66X

15=66X

X=15/66

X= 5/22

There you go.

[chippie]

The answer is wrong.

It's 5 over 22.

-5/3X + 7/3 = -5

-5(3) + 7(3X) = -5(3)(3X)

-15 + 21X = -45X

-15 = -66X

15=66X

X=15/66

X= 5/22

There you go.


The answer is indeed 22 over 5 or 22/5.

-5/3X + 7/3 = -5

(-5/3X + 7/3 = -5) ÷ 3 <-- take the whole equation and divide it by 3.

(-5/3X x 3/1) + (7/3 x 3/1) = (-5 x 3/1)

-5X + 7 = -15

-5X = -15 - 7

-5X = -22

X = -22 ÷ -5

X = 22/5 aka 22 over 5.


To check your answer:

-5/3X + 7/3 = -5

(-5/3 x 22/5) + 7/3 = -5

-22/3 + 7/3 = -5

-15/3 = -5

-5 = -5 <-- It balanced and work!!!

[dan_the_man]

The answer is indeed 22 over 5 or 22/5.

-5/3X + 7/3 = -5

(-5/3X + 7/3 = -5) ÷ 3 <-- take the whole equation and divide it by 3.

(-5/3X x 3/1) + (7/3 x 3/1) = (-5 x 3/1)

-5X + 7 = -15

-5X = -15 - 7

-5X = -22

X = -22 ÷ -5

X = 22/5 aka 22 over 5.


To check your answer:

-5/3X + 7/3 = -5

(-5/3 x 22/5) + 7/3 = -5

-22/3 + 7/3 = -5

-15/3 = -5

-5 = -5 <-- It balanced and work!!!

:rofl: I truly hope you're right (Math isn't my métier). Then I can go up to the Math teacher and tell him he's wrong (yet holds a baccalaureate in Economics, Math, etc.). He told me the answer was 5 over 22. Unbelievable!:lol:

[AlexShymkiw]

:dance: Thanks, it took a little bit longer than expected to get back into the swing of things.

[Mr G]

:rofl: I truly hope you're right (Math isn't my métier). Then I can go up to the Math teacher and tell him he's wrong (yet holds a baccalaureate in Economics, Math, etc.). He told me the answer was 5 over 22. Unbelievable!:lol:

Yeah the answer of 5/22 is right. In the solution you presented, the error was make in the first step of the solution.

[Juice]

The answer is indeed 22 over 5 or 22/5.

-5/3X + 7/3 = -5

(-5/3X + 7/3 = -5) &#247; 3 <-- take the whole equation and divide it by 3.

(-5/3X x 3/1) + (7/3 x 3/1) = (-5 x 3/1)

-5X + 7 = -15

-5X = -15 - 7

-5X = -22

X = -22 &#247; -5

X = 22/5 aka 22 over 5.


To check your answer:

-5/3X + 7/3 = -5

(-5/3 x 22/5) + 7/3 = -5

-22/3 + 7/3 = -5

-15/3 = -5

-5 = -5 <-- It balanced and work!!!
Yeah, it is indeed 5/22. Your mistake happened where I have noted by bolding and underlining. When you multiply -5/3x by 3, you get -5/x, not -5x.

So your solution should look like this:

a) -5/3x + 7/3 = -5

b) 3(-5/3x) + 3(7/3) = 3(-5)

c) -5/x + 7 = -15

d)-5/x = -15 - 7

e) x(-5/x) = x(-22)

f) -5 = -22x

g) -5/-22 = -22x/-22

Therefore:

h) x = 5/22

JB

[N. McKay]

I make it 5/22 as well:

-5/(3x) + 7/3 = -5
-5/(3x) = -5/1 - 7/3
-5/(3x) = -15/3 - 7/3
-5/(3x) = -22/3
5/(3x) = 22/3
5 * 3 = 22 * (3x)
15 = 66x
15/66 = x
5/22 = x

[chippie]

I guess it's time for me to upgrade my math as well :fist:

What I'm confuse is -5/3 of X or -5/(3X)?

I used -5/3 of X and that's how I came up with 22/5 as the answer.

[Juice]

I guess it's time for me to upgrade my math as well :fist:
Don't worry, it took me mulling over it for a day to finally figure it out ;)

JB

[Mr G]

Personally... I'm not 100% sure the question is being interpreted right. Is the 'x' associated with the numerator or the denominator. That would make the answer of 22/5 correct. Something is giving me a strong hunch that's what makes that answer the correct one.

[Juice]

Personally... I'm not 100% sure the question is being interpreted right. Is the 'x' associated with the numerator or the denominator. That would make the answer of 22/5 correct. Something is giving me a strong hunch that's what makes that answer the correct one.
I would imagine the 'x' is being associated with the denominator, making 5/22 the correct answer, as you can see with my solution.

JB

[Mr G]

I would imagine the 'x' is being associated with the denominator, making 5/22 the correct answer, as you can see with my solution.

JB

If the answer was originally quoted as being 22/5, then I can imagine that it was indeed associated with the numerator. I think that perhaps the original poster just wrote out the question incorrectly

[chippie]

Mr. Shymkiw can you scan the equation from your book and post it here? It's starting to bug me trying to figure this out.

[Mr G]

Mr. Shymkiw can you scan the equation from your book and post it here? It's starting to bug me trying to figure this out.

Yeah me too.

[dan_the_man]

Hmmm, somehow I knew that was the right answer (5/22).

[N. McKay]

As the OP has typed it the x belongs, strictly speaking, to the numerator (because you proceed left to right with multiplication and division as you meet them) so 5/3x = 1.667x, the same as 5x/3=1.667x.

My solution assumes that the x belongs to the denominator because it's a little but more intuitive for a person to have typed it that way.

It could be:

5
- x
3

which is equal to

5x
-
3

or it could be

5
-
3x.

The last of these was my assumption.

[Mr G]

As the OP has typed it the x belongs, strictly speaking, to the numerator (because you proceed left to right with multiplication and division as you meet them) so 5/3x = 1.667x, the same as 5x/3=1.667x.

My solution assumes that the x belongs to the denominator because it's a little but more intuitive for a person to have typed it that way.

It could be:

5
- x
3

which is equal to

5x
-
3

or it could be

5
-
3x.

If x belongs to the denominator... 5/(3x) is 1.667/x. You cannot move the x up top.

[AlexShymkiw]

Mr. Shymkiw can you scan the equation from your book and post it here? It's starting to bug me trying to figure this out.

You guys will have to hold out until Saturday morning, my textbook is at home. But I'll be sure to scan it then. :woot:

[N. McKay]

If x belongs to the denominator... 5/(3/x) is 1.667/x. You cannot move the x up top.

If x belongs to the denominator then it's 5/(3x). Where are you getting the extra / between 3 and x?

[Mr G]

If x belongs to the denominator then it's 5/(3x). Where are you getting the extra / between 3 and x?

Mistype on my part... I'll fix that up to avoid any further confusion in this thread.

[AlexShymkiw]

To clarify my original post:

http://www.cadet-world.com/cwforums/attachment.php?attachmentid=4106&d=1175402939

[Juice]

To clarify my original post:

http://www.cadet-world.com/cwforums/attachment.php?attachmentid=4106&d=1175402939
That makes the correct answer 22/5:

1) (-5/3)x + 7/3 = -5

2) 3[(-5/3)x] + 3(7/3) = 3(-5)

3) -5x + 7 = -15

4) -5x = -15 - 7

5) -5x/-5 = -22/-5

6) x = 22/5

JB

[MThornback]

I'm alergic to math...but i'm glad you got an awnser....personally...I took a look at this thread, realized my limitations and turned tail and ran :p

[Conquistador]

Okay all you math whizs out there, I need your help. I'm upgrading Math 11 for post-secondary and I haven't done the course for about two years. My tutor is away at the moment. I'm a little bit rusty so I need your help in solving this review question to prepare for the Chapter test.

-5/3X + 7/3 = -5

The answer is 22/5

Can anyone outline for me what steps I need to take to identify what X is?

-5/(3x) + 7/3 = -5 is equivalent to the simpler equation:

-5/x + 7 = -15 (multiply both sides by 3), or
5/x - 7 = 15 (multiply both sides by -1), which is then equivalent to
5/x = 15 + 7 = 22

Now, taking the reciprocal of both sides, we obtain the expression
x = 22/5, or 22 divided by 5.

A more fundamental way to look at the question is to consider the intersection of the functions f(x) = 5/x and the function g(x ) = 22. The function 5/x is monotonically decreasing (that is, as x gets large, f(x) gets small), and g(x ) is a constant, so there is at most one intersection.

To see this, if a function f(x ) (any function, not necessarily the one in the problem) is strictly decreasing or increasing, that is, always moving up or down in only one direction, then it can cross any single horizontal line once.

[RMC 24409]

There ought to be a formula out there that cancels everything established until now. At least that's not calculus...oh oh, headaches coming back:banghead:

[Conquistador]

The great thing about math is that no established result can ever be overturned (unlike in any other science, where all established results to date are subject to be replaced by a better, more coherent theory), since a mathematical result cannot be 'established' until proven rigorously. For example, the Goldbach Conjecture is almost guaranteed to be true, and many famous mathematicians such as Leonhard Euler have agreed to that sentiment, yet it is still an open problem with no end in sight because no one is able to prove it rigorously.

[RMC 24409]

The great thing about math is that no established result can ever be overturned (unlike in any other science, where all established results to date are subject to be replaced by a better, more coherent theory), since a mathematical result cannot be 'established' until proven rigorously. For example, the Goldbach Conjecture is almost guaranteed to be true, and many famous mathematicians such as Leonhard Euler have agreed to that sentiment, yet it is still an open problem with no end in sight because no one is able to prove it rigorously.

Philosophy can dissaprove anything.

[dan_the_man]

Philosophy can dissaprove anything.

And that is why I wish to study it.:woot:

[Juice]

Philosophy can dissaprove anything.
Not really. Have you ever taken a philosophy course?

JB

[Maples]

I got the chance to take Philosophy at A-level (not sure of Canadian equivalent: sixth form/college exams). Really interesting subject and well worth a go if you like that kind of thing!

[dan_the_man]

Hmm, the conversation seems to have gone from mathematical to philosophical now...still interesting, though. ;)