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**bronxsystem****Member**- Registered: 2013-06-22
- Posts: 63

hey all i have very basic question but i dont understand why my answer is different

i get the answer

however the book says

why cant we remove the -d^2? is it because dividing both negative numbers makes a positive or something S:

*Last edited by bronxsystem (2013-07-15 10:42:08)*

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**bronxsystem****Member**- Registered: 2013-06-22
- Posts: 63

i mean to reduce the fraction

eg 50/50 would just be 1/1 what rule am i missing with the -d^2

prob very silly question but cant get it out of my head

or

this is already reduced right? derp derp (:*Last edited by bronxsystem (2013-07-15 12:11:05)*

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 103,832

Hi;

No, you can reduce that to 1 / 1 = 1

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

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**bronxsystem****Member**- Registered: 2013-06-22
- Posts: 63

how would you write the final answer?

because if i just change the numbers its just 1/1 right S:

sorry i should stop posting after ive stayed up all night

*Last edited by bronxsystem (2013-07-15 16:47:58)*

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 103,832

Hi;

I meant this one.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

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**rete****Member**- Registered: 2013-07-13
- Posts: 12

sorry to bug in, but here is were the logic you have fails, and the book is right

instead of having a-d and a+d, make the a-d=m and a+d=n

what you got:

d/m+a/n=(dn-am)/mn

ok, plug in the stuff

(d(a-d)-a(a+d))/((a+d)(a-d))

big excalmation point, sighn warnings

now if you split them the top part

da-dd-aa-ad=-dd-aa

bottom

(aa+ad-ad+dd)=aa-dd

simplification is only posible is some cases!!!

the a is a variable(wich i am assuming) so is b

if you go with a =7 and d = 1

thy them out

what do you have

7/(1+7)-1/(1-7)=7/8+1/6=25/24

to the formula you have got you get a minus(aa+dd) wich is allways negative or 0 and the solution is positive

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**bronxsystem****Member**- Registered: 2013-06-22
- Posts: 63

hey rete thanks for reply

i followed what you wrote makes sense

*Last edited by bronxsystem (2013-07-16 03:42:58)*

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