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Q: Three Math Equations ( No Answer,   5 Comments )
Subject: Three Math Equations
Category: Reference, Education and News > Homework Help
Asked by: mreyland-ga
List Price: $6.50
Posted: 20 Jul 2006 08:13 PDT
Expires: 21 Jul 2006 22:50 PDT
Question ID: 748001
I need answers to these three math questions.

Directions:  Find all the real solutions.

4/X = (9/5) - ((7X-4)/5X)

(2X - 5)(X+1) = 2


Directions:  Simplify

(3X-9Y) / (9y^2 - X^2)
There is no answer at this time.

Subject: Re: Three Math Equations
From: quocamus-ga on 20 Jul 2006 13:05 PDT
First problem:
4/X = (9/5) - ((7X-4)/5X)
4 = 9X/5 - ((7X-4)/5)
20 = 9X - (7X-4)
20 = 9X - 7X - 4
24 = 2X
X = 12

Second problem:
(2X - 5)(X+1) = 2
2X^2 + 2X - 5X - 5 = 2
2X^2 - 3X - 7 = 0
Using the quadratic formula:
X = (3 +/- sqrt((-3)^2 - 4*2*(-7))) / (2*2)
X = (3 +/- sqrt(9+56)) / 4
X = (3 +/- sqrt(65)) / 4

Third problem:
(3X-9Y) / (9Y^2 - X^2)
= -3(3Y-X) / ((3Y+X)*(3Y-X))
= -3 / (3Y+X)
Subject: Re: Three Math Equations
From: mreyland-ga on 21 Jul 2006 01:35 PDT
Did you not want to list this under the answer to the question?
Subject: Re: Three Math Equations
From: tr1234-ga on 21 Jul 2006 07:57 PDT
"Did you not want to list this under the answer to the question?"

Only official Google Answers researchers are allowed to officially
answer questions. The rest of us only get to post comments. Official
researchers' names appear in blue; since quocamus does not, I presume
he/she is not an official researcher.

You can keep the question open until an official researcher officially
posts an official answer, but if you're satisfied with what you get in
the comments, I'm pretty sure you can close our your question.

Were you to do so, though, I'd suggest double checking quocamus's work
in the first question, 'cuz there's a mistake there in one of the
early steps that resulted in the wrong answer to the problem...
Subject: Re: Three Math Equations
From: mreyland-ga on 21 Jul 2006 10:03 PDT
Yes, I know.  When I was working the problem out that was the answer I
kept getting, but if you go back and plug it in it doesn't work.  I
just can't for the life of me, figure out what the answer is.
Subject: Re: Three Math Equations
From: thither-ga on 21 Jul 2006 10:33 PDT
20 = 9X - (7X-4)
20 = 9X - 7X - 4

It should be 20 = 9X - 7X + 4

X = 8

Have a good day.

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