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If x≠4, what is the range of the solutions of the equation |14–x|=24/(

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If x≠4, what is the range of the solutions of the equation |14–x|=24/(  [#permalink]

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New post 28 Apr 2017, 03:04
1
26
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A
B
C
D
E

Difficulty:

  85% (hard)

Question Stats:

64% (02:47) correct 36% (03:12) wrong based on 348 sessions

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CEO
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Re: If x≠4, what is the range of the solutions of the equation |14–x|=24/(  [#permalink]

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New post 28 Apr 2017, 06:46
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Top Contributor
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Bunuel wrote:
If x≠4, what is the range of the solutions of the equation |14–x|=24/(x−4)?

A. 2
B. 6
C. 8
D. 20
E. 32


There are 3 steps to solving equations involving ABSOLUTE VALUE:
1. Apply the rule that says: If |x| = k, then x = k and/or x = -k
2. Solve the resulting equations
3. Plug solutions into original equation to check for extraneous roots

Given: |14–x|=24/(x−4)

So, we need to check 14–x = 24/(x−4) and 14–x = -24/(x−4)

14–x = 24/(x−4)
Multiply both sides by (x-4) to get: (14–x)(x−4) = 24
Expand: -x² + 18x - 56 = 24
Rearrange to get: x² - 18x + 80 = 0
Factor: (x - 10)(x - 8) = 0
So, x = 10 or x = 8

Test each solution:
If x = 10, then we get: |14–10|=24/(10−4)
Simplify: |4|=4 PERFECT!
So, x = 10 is a possible solution

If x = 8, then we get: |14–8|=24/(8−4)
Simplify: |6|=6 PERFECT!
So, x = 8 is a possible solution

14–x = -24/(x−4)
Multiply both sides by (x-4) to get: (14–x)(x−4) = -24
Expand: -x² + 18x - 56 = -24
Rearrange to get: x² - 18x + 32 = 0
Factor: (x - 2)(x - 16) = 0
So, x = 2 or x = 16

Test each solution:
If x = 2, then we get: |14–2|=24/(2−4)
Simplify: |12|=-12 DOESN'T WORK
So, x = 2 is NOT a possible solution

If x = 16, then we get: |14–16|=24/(16−4)
Simplify: |-2|=2 PERFECT!
So, x = 16 is a possible solution

So, the possible solutions are 8, 10 and 16
Range = 16 - 8 = 8

Answer:

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Re: If x≠4, what is the range of the solutions of the equation |14–x|=24/(  [#permalink]

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New post 28 Apr 2017, 06:39
2
|14 - x| = 24/(x - 4)

(x - 4)(14 - x) = 24
x^2 - 18x + 80 = 0
x = 8 or 10

(x - 4)(14 - x) = -24
x^2 - 18x + 32 = 0
x = 16 or 2 but 2 is not a valid solution since \(|14 - 2| \neq {-12}\)

Range = 16 - 8 = 8

Answer: C
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Re: If x≠4, what is the range of the solutions of the equation |14–x|=24/(  [#permalink]

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New post 13 Jul 2017, 18:40
Bunuel wrote:
If x≠4, what is the range of the solutions of the equation \(|14–x|=\frac{24}{(x−4)}\)?

A. 2
B. 6
C. 8
D. 20
E. 32


pushpitkc , Is it possible to solve this question using the number line?

It took me more than 2 minutes to solve this question. I normally prefer the number line, but in this case I just couldn't use it.
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Re: If x≠4, what is the range of the solutions of the equation |14–x|=24/(  [#permalink]

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New post 16 Jul 2018, 10:14
Bunuel wrote:
If x≠4, what is the range of the solutions of the equation \(|14–x|=\frac{24}{(x−4)}\)?

A. 2
B. 6
C. 8
D. 20
E. 32


Given: \(|14–x|=\frac{24}{(x−4)}\)

For 14 - x > 0, we have x < 14

(14-x)(x-4) = 24, solving we get x = 10 or 8 < 14, hence both solutions are good.

For 14 - x < 0, we have x > 14

(x-14)(x-4) = 24. solving we get x = 2 or 16, only x = 16 > 14 is good.

hence we have x = 8, 10, 16

Range of Solutions = 16 - 8 = 8


Answer C.


Thanks,
GyM
Re: If x≠4, what is the range of the solutions of the equation |14–x|=24/( &nbs [#permalink] 16 Jul 2018, 10:14
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