MHB What are the solutions to this absolute value equation?

AI Thread Summary
The discussion focuses on solving the absolute value equation |1/2x + 1| = |x|. The correct solutions identified are x = 2 and x = -2/3, with a clarification on the interpretation of the equation's format. Two cases are derived: one leading to a quadratic equation with real solutions, and the other resulting in complex solutions. Participants emphasize the importance of clarity in mathematical notation to avoid confusion. Overall, the conversation highlights both the correct solutions and the need for precise expression in mathematical equations.
Alexstrasuz1
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I have trouble solving this equation
|1/2x+1|=|x|

My answers are x=2 and x=-2/3
 
Last edited:
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corrected mistake in (2) as pointed out by MarkFL in the successive post...

Alexstrasuz said:
I have trouble solving this equation
|1/2x+1|=|x|

My answers are x=2 and x=-2/3

An easy way is to find the solution of the equations...

$\displaystyle \frac{1}{2 x} + 1 = x \implies 2\ x^{2} - 2\ x - 1 =0 \implies x = \frac{1 \pm \sqrt{3}}{2}\ (1)$

$\displaystyle \frac{1}{2 x} + 1 = - x \implies 2\ x^{2} + 2\ x + 1 =0 \implies x = \frac{- 1 \pm i}{2}\ (2)$

Kind regards

$\chi$ $\sigma$

P.S. MarlFL has 'discovered' a mistake in (2) and I corrected it... sorry!...
 
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chisigma said:
An easy way is to find the solution of the equations...

$\displaystyle \frac{1}{2 x} + 1 = x \implies 2\ x^{2} - 2\ x - 1 =0 \implies x = \frac{1 \pm \sqrt{3}}{2}\ (1)$

$\displaystyle \frac{1}{2 x} + 1 = - x \implies 2\ x^{2} + 2\ x - 1 =0 \implies x = \frac{- 1 \pm \sqrt{3}}{2}\ (2)$

Kind regards

$\chi$ $\sigma$

The second equation should be:

$$2x^2+2x+1=0\implies x=\frac{-1\pm i}{2}$$
 
Alexstrasuz said:
I have trouble solving this equation
|1/2x+1|=|x|

My answers are x=2 and x=-2/3

Yes, your answers are correct.
Other posts were solving...
|1/2/x+1|=|x|
 
RLBrown said:
Yes, your answers are correct.
Other posts were solving...
|1/2/x+1|=|x|

Just to be clear, I was solving:

$$\left|\frac{1}{2x}+1\right|=|x|$$

More often than not, when someone uses 1/2x, they mean 1/(2x) as opposed to (1/2)x.

This is why is is better to use bracketing symbols (or even better, use $\LaTeX$) to remove doubt. :D
 
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