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How to solve equation with unknown in the denominator eg 2x+3/x-4 - 2x-8/2x+1=1

 Apr 17, 2016

Best Answer 

 #3
avatar+129849 
+5

(2x+3) / (x-4) - (2x-8) / (2x+1) =1    multiply both sides by the common denominator  of (x -4)(2x + 1)

 

So we have....

 

(2x + 3)(2x+ 1)  - [(2x - 8)(x -4)]  = (x -4)(2x + 1)   simplify

 

4x^2 + 8x + 3 - [ 2x^2 - 16x + 32]  = 2x^2 - 7x - 4

 

2x^2 + 24x  -29 =  2x^2 - 7x - 4

 

Subtract 2x^2 from both sides........add 7x, 29 to both sides

 

31x = 25      divide both sides by 31

 

x = 25 / 31

 

 

 

cool cool cool

 Apr 17, 2016
 #1
avatar+154 
+5

What you do is that you time the denominator with the number diagonally opposite.

You will get (2x+3)(2x+1)-(x-4)(2x-8)=1

It is now an wasy quadratic equation which can now be solved easily :)

 Apr 17, 2016
 #2
avatar+154 
+5

By the way im back!!!

Sorry for the absence, hopefully it wont happen again until June (When i have my very important maths exam)

 Apr 17, 2016
 #3
avatar+129849 
+5
Best Answer

(2x+3) / (x-4) - (2x-8) / (2x+1) =1    multiply both sides by the common denominator  of (x -4)(2x + 1)

 

So we have....

 

(2x + 3)(2x+ 1)  - [(2x - 8)(x -4)]  = (x -4)(2x + 1)   simplify

 

4x^2 + 8x + 3 - [ 2x^2 - 16x + 32]  = 2x^2 - 7x - 4

 

2x^2 + 24x  -29 =  2x^2 - 7x - 4

 

Subtract 2x^2 from both sides........add 7x, 29 to both sides

 

31x = 25      divide both sides by 31

 

x = 25 / 31

 

 

 

cool cool cool

CPhill Apr 17, 2016
 #4
avatar+154 
0

ohhhh yes.

I completely forgot to times 1 by the two equations...

Im an idiot.

Anyway good working Cpill, hope you appreciate the 5 stars :)

 Apr 17, 2016
 #5
avatar+129849 
+5

Eh, you're not an idiot, Mathaholic......your answers are usually pretty good.....thanks for the "stars"

 

 

 

cool cool cool

 Apr 17, 2016

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