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June 23rd, 2017, 06:42 PM   #1
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A possible algebra's law violation

Hello guys.... I'm new here and I hope to make friends here, learn and share my knowledge.


Well, my first one is going to be two literal compound quantities that must be subtracted:


From the binomial A + B subtract A - B. This proposed problem is very easy solution, so that I'll do it and according to algebraic rules:


A + B
sub A - B
-------

step 1. A + B - A - B
step 2. A + B - (A - B)
step 3. A + B - A + B
step 4. A - A + B + B
final step. 2B



Is the final step the right solution? Did I calculate it wrong? Is there really any violation?


Please guys answer me. I'll be very thankful.

Thanks a lot for the attention.

Last edited by skipjack; June 24th, 2017 at 05:31 AM.
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June 23rd, 2017, 06:59 PM   #2
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Yeah, it's the right solution Why do you have doubts about it?
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June 23rd, 2017, 07:05 PM   #3
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123quwerty thanks alot for the attention
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June 24th, 2017, 07:24 AM   #4
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Step 1 was incorrect notation.

When you are considering compound entities such as (A+B) or (A-B) always put them in brackets to start with.


So step1 should be

(A+B) - (A-B)

People often get their algebra muddled and wrong if they do not do this.
Thanks from EvanJ and Jeff Guercio

Last edited by skipjack; June 24th, 2017 at 01:19 PM.
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June 28th, 2017, 09:32 AM   #5
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Ohhh studiot thanks alot for the answer now I got to the point I'd like.....


We know this is simple stuff to do, even so these algebraic rules are big trouble if not followed rightly.

Yah yah your answer make total sense . Therefore I thought it was about to change the result.


By the way my doubt is in STEP3:

Would this be the reminder (A+B) - (A + B) ?

Hence the proof:

A - B ----> the subtractor + the reminder -----> (A + B) - (A + B) = A + B


Also, weren't these quantities to be extinguished just before the final step?



Well...this small reference I took from John Kersy's algebra book and this part called me some attention indeed it seems a few archaic, cause in some parts of his book he didn't mention the use of brackets in compounds, instead he uses lines over their compounds.

Examples:

_____ _____
A + B - A + B is the same as (A + B) - (A + B) showing an old notation form.




Thanks alot one more time for the attention guys!!

Last edited by skipjack; August 7th, 2017 at 08:00 AM.
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