Math Is Fun Forum

bronxsystem

Member

Registered: 2013-06-22

Posts: 63

combining algebra fractions

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)

bronxsystem

Member

Registered: 2013-06-22

Posts: 63

Re: combining algebra fractions

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)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: combining algebra fractions

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.
Always satisfy the Prime Directive of getting the right answer above all else.

bronxsystem

Member

Registered: 2013-06-22

Posts: 63

Re: combining algebra fractions

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)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: combining algebra fractions

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.
Always satisfy the Prime Directive of getting the right answer above all else.

rete

Member

Registered: 2013-07-13

Posts: 12

Re: combining algebra fractions

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

bronxsystem

Member

Registered: 2013-06-22

Posts: 63

Re: combining algebra fractions

hey rete thanks for reply

i followed what you wrote makes sense

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