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The following needs to be simplified. I have given up after 1 hour and 7 pages. i will write it out in words to make it easier to understand.

Simplifiy:
(a plus b over a minus b) minus (a minus b over a plus b)

Basically.
(a+b/a-b)-(a-b/a+b)
or
a+b______a-b
a-b ___-___a+b (ignore the lines)
I keep getting an answer of zero which is incorrect.

2007-05-02 07:07:58 · 14 answers · asked by Fool 2 in Science & Mathematics Mathematics

14 answers

(a+b)/(a-b) - (a-b)/(a+b) = ...

the common denominator for both fractions is (a-b)(a+b)
=> multiply the first fraction (top and bottom) by (a+b) and the second one by (a-b)

= (a+b)·(a+b)/(a-b)·(a+b) - (a-b)·(a-b)/(a+b)·(a-b) =

= (a+b)² /(a-b)·(a+b) - (a-b)² /(a+b)·(a-b) =

= [ (a+b)² - (a-b)² ] /(a-b)·(a+b) =

= [ a² + 2ab + b² - (a² - 2ab + b²) ] /(a-b)·(a+b) =

4ab /(a-b)·(a+b)

(or 4ab /(a²-b²) )

Hope this helps.

2007-05-02 07:11:47 · answer #1 · answered by M 6 · 8 1

I think you are not distributing correctly somewhere in your 7 pages.

You need to get the common denominator, which will be (a+b)(a-b) and that equals a^2-b^2.

Your first fraction is then (a+b)(a+b) / (a-b)(a+b) which equals (a^2+2ab+b^2) / (a^2-b^2).

Your second fraction is (a-b)(a-b) / (a-b)(a+b) which equals
(a^2-2ab+b^2)/(a^2-b^2).

Subtract them, and the numerators give
(a^2+2ab+b^2) - (a^2-2ab+b^2) = a^2 + 2ab + b^2 - a^2 + 2ab - b^2 = 4ab.

Therefore your answer will be 4ab / (a^2-b^2)

2007-05-02 07:18:45 · answer #2 · answered by Anonymous · 1 0

You are required to subtract two fractions

You need a common denominator (a+b)(a-b)

Multiply top and bottom of first fraction by a + b
Multiply top and bottom of second fraction by a - b

You will then have

(a+b)(a+b)/ (a+b)(a-b) minus (a-b)(a-b)/(a+b)(a-b)

numerator is (a^2 + 2ab + b^2) minus (a^2 - 2ab + b^2)
denominator is (a + b)(a - b)

numerator simplifies to 4ab so your answer is

4ab/[(a+b)(a-b)]

2007-05-02 07:22:44 · answer #3 · answered by fred 5 · 0 0

(a + b) / (a - b) - (a - b)/(a + b)

You need a common denominator of (a - b)(a + b)

So...
The first fraction becomes:
(a + b)(a + b) / (a - b)(a + b)
= (a^2 + 2ab + b^2) / (a - b)(a + b)

And the second one:
(a - b)(a - b) / (a - b)(a + b)
= (a^2 - 2ab + b^2) / (a - b)(a + b)

Now, you're subtracting those.... I'm just going to work on the numerators for a minute...

(a^2 + 2ab + b^2) - (a^2 - 2ab + b^2)
= a^2 + 2ab + b^2 - a^2 + 2ab - b^2
(Make sure you distribute that minus sign correctly!!!)
= 4ab

So, the final answer is

4ab / (a - b)(a + b)

2007-05-02 07:14:56 · answer #4 · answered by Mathematica 7 · 2 3

First, please verify that the parentheses that I have inserted correctly describe the expression:
f = (a+b)/(a-b) - (a-b)/(a+b).
Multiply and divide through by (a+b)(a-b) to get:
((a+b)^2 - (a-b)*2)/((a+b)(a-b))
Expand the numerator and denominator:
(a*2 + 2ab + b*2 - a*2 + 2ab - b*2)/(a^2 - b^2)
Collect terms:
4ab/(a^2 - b*2). Done.

2007-05-02 07:20:14 · answer #5 · answered by Anonymous · 0 0

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2016-12-05 05:48:47 · answer #6 · answered by headlee 4 · 0 0

I think you mean (a+b)/(a-b) - (a-b)/(a+b), in which case

[(a+b)(a+b)] / [(a-b)(a+b)] - [(a-b)(a-b)] / [(a+b)(a-b)] =

= [(a+b)^2 - (a-b)^2] / [(a-b)(a+b)]

= [a^2 + 2ab + b^2 - (a^2 - 2ab + b^2)] / [a^2 - ba + ab - b^2]

= (4ab) / (a^2 - b^2).

2007-05-02 07:17:26 · answer #7 · answered by victeric 3 · 0 0

Call Me Pete is correct (dang, not fast enough!)

You could FOIL the bottom into what John, M, and Adam have, though. I think some of these people are changing their answers to be correct lol

2007-05-02 07:17:14 · answer #8 · answered by Randy 4 · 0 1

(a+b/a-b) - (a-b/a+b) =
= (a+b)*2 - (a-b)*2 /(a-b)(a+b) =
= a*2+2ab+b*2-a*2+2ab-b*2/(a-b)(a+b)
= 4ab/(a-b)(a+b)

*2 means exponent

2007-05-02 07:33:15 · answer #9 · answered by jasmina z 1 · 0 0

(a+b/a-b) - (a-b/a+b)
= [(a+b)^2/(a-b)(a+b)] - [(a-b)^2/(a+b)(a-b)]
= [(a+b)^2 - (a-b)^2] / (a+b)(a-b)
= [a^2 + 2ab + b^2 - a^2 + 2ab - b^2] / (a+b)(a-b)
= 4ab / (a^2 - b^2)

2007-05-02 14:09:06 · answer #10 · answered by Kemmy 6 · 0 0

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