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# If square_root of (X - 1) - 7 = -x, then x is equal to

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SC Moderator
Joined: 25 Sep 2018
Posts: 872
Location: United States (CA)
Concentration: Finance, Strategy
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If square_root of (X - 1) - 7 = -x, then x is equal to  [#permalink]

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31 Jul 2019, 06:09
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Difficulty:

45% (medium)

Question Stats:

54% (01:20) correct 46% (01:45) wrong based on 56 sessions

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If $$\sqrt{X - 1}$$ - 7 = -x, then x is equal to which of the following

i. 10
ii . 5
iii. 1

A) i only
B) ii only
C) iii only
D) i & ii
E) i , ii & iii

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Joined: 15 Aug 2017
Posts: 24
If square_root of (X - 1) - 7 = -x, then x is equal to  [#permalink]

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31 Jul 2019, 07:16
$$\sqrt{X-1} - 7 = -x$$

$$\sqrt{X-1} = -x + 7$$

i. 10
$$\sqrt{10 - 1} = -(10) + 7$$
$$\sqrt{9} = -3$$
$$3 = -3$$
Doesn't equal

ii. 5
$$\sqrt{5 - 1} = -(5) + 7$$
$$\sqrt{4} = 7$$
$$2 = 2$$
Equals

IIi. 0
$$\sqrt{0 - 1} = -(0) + 7$$ < -- cannot sqrt negatie number
Doesn't equal

IMO B.
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Joined: 09 May 2018
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Re: If square_root of (X - 1) - 7 = -x, then x is equal to  [#permalink]

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15 Aug 2019, 06:21
When I did it with squaring both the sides after taking 7 RHS, I get 10 and 5 as roots. Am i doing something wrong here or what is the issue?
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Re: If square_root of (X - 1) - 7 = -x, then x is equal to  [#permalink]

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15 Aug 2019, 10:44
Abhi077 wrote:
If $$\sqrt{X - 1}$$ - 7 = -x, then x is equal to which of the following

i. 10
ii . 5
iii. 1

A) i only
B) ii only
C) iii only
D) i & ii
E) i , ii & iii

No need of any calculation for this question, test using the given answer options mentally its matter of 10 secs....

$$\sqrt{5 - 1} - 7 = -5$$

Or, $$2 - 7 = -5$$, Answer must be (B)
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Abhishek....

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Re: If square_root of (X - 1) - 7 = -x, then x is equal to   [#permalink] 15 Aug 2019, 10:44

# If square_root of (X - 1) - 7 = -x, then x is equal to

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