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Quick math question, Got the answer just need help solving the problem?
(2)/(x+1)-(1)/(x-1)=(2x)/(x^2-1)
I know that the answer is x=-3
I just need help trying to understand how to answer it
3 Answers
- Pramod KumarLv 79 years agoFavorite Answer
Mark's Method is 100% correct. But I have got another way to go ahead. --
......... 2...............1.............2 x
=> ----------- - -------------- = -------------
.....(x + 1)....... ( x - 1 ). .. . .x² - 1
......... 2...............1.................2 x
=> ----------- - -------------- = -------------------
.....(x + 1)....... ( x - 1 ). . . . (x-1).(x+1)
Multiply the whole eqn by (x-1).(x+1) we get ---
=> 2 ( x - 1 ) - 1 ( x + 1 ) = 2 x
=> 2 x - 2 - ( x + 1 ) - 2 x = 0
=> 2 x - 2 - x - 1 - 2 x = 0
=> x = - 3 ............... Answer Answer
>>>>>>>>>>>>>>>>>
.
- Mark WaltherLv 49 years ago
You need to recognize that (x+1)(x-1) = (x^2-1) is a difference of two squares, so multiplying by (x^2-1)/(x^2-1) on both sides for every term makes it so that:
(2)/(x+1) - (1)/(x-1) = (2x)/(x^2-1)
equals
(2)(x-1) - (1)(x+1) = 2x
equals
2x - 2 - x - 1 = 2x
x - 3 = 2x
-3 = x
Then you check by plugging -3 back in to make sure it's extraneous, but of course it's not because there's nothing in the denominator that makes it undefined. ;)
Source(s): Pre-Calculus last year. - ?Lv 44 years ago
you may factor each and every. 2x + 2y = 10 2 (x + y) = 2 (5) x+y = 5 -2x - 2y = 4 -2 (x + y) = -2 (-2) x + y = -2 you have an impossible gadget. x + y won't be able to equivalent 5 AND - 2. So the gadget has no recommendations.