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# If (x + 3)2 = 225, which of the following could be the value

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If (x + 3)2 = 225, which of the following could be the value [#permalink]  17 Jul 2018, 11:37
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Question Stats:

50% (01:14) correct 49% (01:00) wrong based on 65 sessions
If $$(x + 3)^2 = 225$$, which of the following could be the value of $$x - 1$$?

(A) 13
(B) 12
(C) –12
(D) –16
(E) –19
[Reveal] Spoiler: OA

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Sandy
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Re: If (x + 3)2 = 225, which of the following could be the value [#permalink]  18 Jul 2018, 12:25
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sandy wrote:
If $$(x + 3)^2 = 225$$, which of the following could be the value of $$x - 1$$?

(A) 13
(B) 12
(C) –12
(D) –16
(E) –19

Given

$$(x + 3)^2$$ = 225

x + 3 = 15 or -15

Note: 15*15 =225 or -15*(-15) =225

So we will have 2 sets of values here.

Case 1 :

x + 3 = 15

x = 12

Case 2 :

x + 3 = -15

x = -18.

Question : the value of x-1.

-18 -1 = -19

Option E fits.
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Re: If (x + 3)2 = 225, which of the following could be the value [#permalink]  10 Apr 2019, 06:02
1
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I tried a different approach:

If A) x-1=13 > x=14

Then,

B) x=13
C) x=-11
D) x=-15
E) x=-18

As (x+3)^2=225, I need to pick one option equal to 225
A) (14+3)^2= 225
B) (13+3)^2 =225
C) (-11+3)^2= 225
D) (-15+3)^2= 225

E) (-18+3)^2= 225

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Re: If (x + 3)2 = 225, which of the following could be the value [#permalink]  08 May 2020, 04:32
I'm wondering why this one has so few correct answers. A lot of the time on the GRE quant I start to think diagnosing why so many get something wrong is better than diagnosing how they got it right.

Guessing most just root each side, see their answer of 11 doesn't exist, and guess. Key here is that when you take the root of a variable you have to set whatever was rooted to an absolute value. The absolute value must be considered as both possibly being positive and possibly being negative. Solve for each.
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Re: If (x + 3)2 = 225, which of the following could be the value [#permalink]  29 May 2020, 00:31
If 15-3=12
Then x-1 = 12-1=-11 is the right ans which is not visible in ans choices.

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Re: If (x + 3)2 = 225, which of the following could be the value   [#permalink] 29 May 2020, 00:31
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# If (x + 3)2 = 225, which of the following could be the value

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