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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. ### Request Expert Reply # If x = 4, then −2^{2 x^1/2} + 2 =?

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Senior RC Moderator V
Joined: 02 Nov 2016
Posts: 3478
GPA: 3.39
If x = 4, then −2^{2 x^1/2} + 2 =?  [#permalink]

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3 00:00

Difficulty:   45% (medium)

Question Stats: 44% (00:37) correct 56% (00:42) wrong based on 61 sessions

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If $$x = 4$$, then $$−2^{2 \sqrt{x}} + 2 =$$?

(A) –14
(B) –8
(C) –2
(D) 0
(E) 18

Source: Nova GMAT
Difficulty Level: 650

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Manager  S
Joined: 25 Jul 2018
Posts: 203
Re: If x = 4, then −2^{2 x^1/2} + 2 =?  [#permalink]

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If x=4, then √4=2.
-2^4+2= -16+2=-14.
Answer choice is A.

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Intern  B
Joined: 27 Jun 2019
Posts: 2
Re: If x = 4, then −2^{2 x^1/2} + 2 =?  [#permalink]

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If x=4 then √x=2
=> 2√x=4
=> (-2)^4= 16
=> 16+2=18
Answer has to be E

Posted from my mobile device
Senior Manager  G
Joined: 20 Mar 2018
Posts: 269
Location: Ghana
Concentration: Finance, Real Estate
Re: If x = 4, then −2^{2 x^1/2} + 2 =?  [#permalink]

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-2^4 is not equal to (-2)^4
Let’s see why
-2^4 =(-1)(2)^4=-16
(-2)^4 =-2•-2•-2•-2=16
Hope it helps
Amarjoth wrote:
If x=4 then √x=2
=> 2√x=4
=> (-2)^4= 16
=> 16+2=18
Answer has to be E

Posted from my mobile device
Intern  B
Joined: 27 Jun 2019
Posts: 2
Re: If x = 4, then −2^{2 x^1/2} + 2 =?  [#permalink]

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In that case it must be explicitly mentioned as
-(2)^2√x which will clear out ambiguity by writing it as -2^2√x it can be interpreted in 2 manners

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Math Expert V
Joined: 02 Sep 2009
Posts: 57279
Re: If x = 4, then −2^{2 x^1/2} + 2 =?  [#permalink]

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3
Amarjoth wrote:
In that case it must be explicitly mentioned as
-(2)^2√x which will clear out ambiguity by writing it as -2^2√x it can be interpreted in 2 manners

Posted from my mobile device

Nope. Everything is correct there.

$$−2^{2 \sqrt{x}}$$ can only mean $$−(2^{2 \sqrt{x}})$$ and not $$(−2)^{2 \sqrt{x}}$$. If it were $$(−2)^{2 \sqrt{x}}$$ it would have been written that way.
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Senior Manager  G
Joined: 20 Mar 2018
Posts: 269
Location: Ghana
Concentration: Finance, Real Estate
Re: If x = 4, then −2^{2 x^1/2} + 2 =?  [#permalink]

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Bunuel
(my Maths genius) has explained it above
Amarjoth wrote:
In that case it must be explicitly mentioned as
-(2)^2√x which will clear out ambiguity by writing it as -2^2√x it can be interpreted in 2 manners

Posted from my mobile device Re: If x = 4, then −2^{2 x^1/2} + 2 =?   [#permalink] 19 Jul 2019, 06:06
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# If x = 4, then −2^{2 x^1/2} + 2 =?

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