Jennifer R.

asked • 08/21/16

what do you do in complex fractions

when your at 25a - a2 / 5a + a2 ?

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Chunli M. answered • 08/21/16

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  (25a - a)2 / (5a + a)2
 
= (24a)2 / (6a)2
 
= 242 / 62
 
= 16
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Jennifer R.

i accidentally wrote it wrong
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08/21/16

Chunli M.

  25a - a2 / 5a + a2 
 
= a (25 - a) / a (5 + a)
 
= (25 - a) / (5 + a)
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08/21/16

Chunli M.

 
Hi Jennifer, 
 
your question is (25a - a2) / (5a + a2) 
 
or without bracket like this 25a - a2 / 5a + a2
 
I answer your comment in this two ways
 
option 1:
 
 (25a - a2) / (5a + a2)
 
= a (25 - a) / a (5 + a)

= (25 - a) / (5 + a)
 
option 2:
 
  25a - a2 / 5a + a2
 
= 25a - a/5 + a2
 
= 124/5 a + a2 
 
 
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08/21/16

Jennifer R.

thank you for taking time out of your day it was option 2
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08/21/16

Chunli M.

It is my pleasure to help you
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08/21/16

Jennifer R.

im confused where is the 124 from 
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08/21/16

Chunli M.

  25a - a/5
 
= 125/5 a - a/5
 
= (125 - 1)/5 a
 
= 124 / 5 a
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08/21/16

Jennifer R.

the problem is 25/a - a/ 5 + a then i did some work and got stuck which is the option 2 one that i asked do you think i am doing something wrong
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08/21/16

Chunli M.

it is not 25/a, it is 25*a
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08/21/16

Jennifer R.

i wrote it wrong: 25   _   a/
                           a 
                                          
                          5 + a
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08/21/16

Jennifer R.

it is 25 divided by a minus a then all of that is divided by five plus a 
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08/21/16

Chunli M.

  25/a - a/ 5 + a
 
= 25/a + 4/5 a
 
= 25 * 5 /(5a) + 4*a *a/ (5a) 
 
= (125 + 4a2)/ (5a)
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08/21/16

Chunli M.

I think your expression like this, if it is not right, could you please write to me with bracket? Thank you
 
   [25/(-a)] / (5 + a)
 
= - 25 / [a * (5 + a)]
 
= - 25 / (5a + a2)
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08/21/16

Jennifer R.

was i doing it wrong then i did, 
25/a - a/ 5+a * a/1/a/1
= 25/a * a/1 - a/1 * a/1 / 5/1 * a/1 + a/1 * a/1 
=25a - a2/5a+a2
=
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08/21/16

Jennifer R.

[25/a - a]/5+a
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08/21/16

Chunli M.

I  answer your question one by one 
 
25/a - a/5 + a
the greatest common divisor is 5a
so this expression the denominator should be 5a 
so you miss 5 in the denominator, then the result is wrong
 
 
 
 
 
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08/21/16

Jennifer R.

so instead of multiplying the problem with a divided by 1 divided by a divided by 1 i need to divide it with 5a divided by 1 divided by 5a divided by 1 or is it 5a divided by 5a 
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08/21/16

Chunli M.

[25/a - a]/5+a
 
according to the expression you write, I think it is divide by 5 not divide by 5+a
 
first step
 
  [25/a - a]/5  + a 
 
= (25/a - a2/a) / 5 + a
 
= (25 - a2) / (5a) + a
 
= (25 - a2) / (5a)  + 5a2 / (5a)
 
= (25 - a2 + 5a2) / (5a)
 
= (25 + 4a2) / (5a)
 
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08/21/16

Jennifer R.

can i ask you something if i am not understanding thi and this is summer hw then ho will i do in clas do you think i should still take calculus 
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08/21/16

Chunli M.

It is my pleasure to help you
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08/21/16

Jennifer R.

in the second part of the problem how did you get a2
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08/21/16

Chunli M.

a2 = a*a
 
because I multiply a in the denominator, so the numerator also have to multiply a, then numerator is a * a = a2
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08/21/16

Jennifer R.

thank you 
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08/21/16

Chunli M.

You are welcome, if you have any other question, please let me know
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08/21/16

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