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|x+7|?

by crackgmat007 » Fri May 22, 2009 8:10 am
What is the value of │x + 7│?
(1) │x + 3│= 14
(2) (x + 2)^2 = 169
Answer C
Last edited by crackgmat007 on Fri May 22, 2009 8:09 pm, edited 2 times in total.
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by DanaJ » Fri May 22, 2009 8:25 am
1. tells you that |x + 3| = 14, which means that:
a. x + 3 = 14, when you get x = 11
b. x + 3 = -14, when you get x = -17
Then calculate |x + 7| for both cases:
a. x = 11 --- |x + 7| = |18| = 18
b. x = -17 --- |x + 7| = |-10| = 10

You get two answers, so IMHO A isn't sufficient.

2. means that (x + 2)^2 = 169 = 13^2 = (-13)^2 - this is why you have two cases as well:
a. x + 2 = 13 --- x = 11 --- |x + 7| = |18| = 18
b. x + 2 = -13 --- x = -15 --- |x + 7| = |-8| = 8

Again, you get two answers.
But put both stmts together to get single answer 18. This is why the answer is IMHO C.
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by sanjay_dce » Fri May 22, 2009 11:19 am
C be it
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Re: |x+7|?

by maihuna » Sun May 24, 2009 11:16 am
crackgmat007 wrote:What is the value of │x + 7│?
(1) │x + 3│= 14
(2) (x + 2)^2 = 169
Answer C
x+3 = 14=> x=11 so x+7 = 18 |x+7| = 18
x+13 = -14 =>x=-17 so x+7 = -10 => |x+7| = 10

2. x+2 = 13 => x = 11
x+2 = -13 =>x = -15

combining the above two the common is x = 11 so x+7 = 18
Charged up again to beat the beast :)
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