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If sqrtx+6
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21 Sep 2021, 01:42
21 Sep 2021, 01:42
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Question Stats:
50% (02:52) correct
50% (01:03) wrong based on 4 sessions
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If \(\sqrt{x+6} + \sqrt{x+1}=5\) what is the value of \(x^2\)?
A. 1
B. 4
C. 9
D. 16
E. 25
Source: manhattanreview
A. 1
B. 4
C. 9
D. 16
E. 25
Source: manhattanreview
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Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: If sqrtx+6
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21 Sep 2021, 09:54
21 Sep 2021, 09:54
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Carcass wrote:
If \(\sqrt{x+6} + \sqrt{x+1}=5\) what is the value of \(x^2\)?
A. 1
B. 4
C. 9
D. 16
E. 25
Source: manhattanreview
A. 1
B. 4
C. 9
D. 16
E. 25
Source: manhattanreview
Rather than try to solve this tricky equation, a much faster approach is to test the answer choices.
A. 1
If x² = 1, then x = 1 or -1
If x = 1, we have: \(\sqrt{0+6} + \sqrt{0+1}=5\). Doesn't work!
If x = -1, we have: \(\sqrt{(-1)+6} + \sqrt{(-1)+1}=5\). Doesn't work!
B. 4
If x² = 4, then x = 2 or -2
If x = 2, we have: \(\sqrt{2+6} + \sqrt{2+1}=5\). Doesn't work!
If x = -2, we have: \(\sqrt{(-2)+6} + \sqrt{(-2)+1}=5\). Doesn't work!
C. 9
If x² = 9, then x = 3 or -3
If x = 3, we have: \(\sqrt{3+6} + \sqrt{3+1}=5\). WORKS!!!
Answer: C
gmatclubot
Re: If sqrtx+6 [#permalink]
21 Sep 2021, 09:54
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