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1/(x+1) - 1/(x+2) = 1/2

User Merrissa
by
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1 Answer

2 votes
Please include the instructions; I assume your job is to find the value of x.

1/(x+1) - 1/(x+2) = 1/2 would better be written as

1 1 1
-------- - ------------ = ----
x+1 x+2 2

Identify the LCD. It is (x+1)(x+2)(2). Mult. all 3 terms of the equation by this LCD:

2(x+2) - 2(x+1) = 2(x+1)(x+2)

We can factor out the 2 from all terms:

x+2 - x - 1 = x^2 + 3x + 2

Let's move all terms from the left to the right side:

0 = x^2 + 3x + 2 - x - 2 + x + 1

Then x^2 + 3x + 1 = 0. This is a quadratic with a=1, b=3 and c=1.

What is x?

-3 plus or minus sqrt( 9-4(1)(1) ) -3 plus or minus sqrt(5)
x = --------------------------------------------- = ---------------------------------
2 2

I rather expected to obtain an integer value for x.


Why don't you give this problem a try yourself? Suggestion: First mult. every term by 2. This will give you:

2 2
------- - ------- = 1 and this may be slightly easier to work with. Please
x+1 x+2 give it a try: try to find x that satisfies this equation.
Important: note that x cannot equal either -1 or -2.


User Mikko Viitala
by
6.8k points
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