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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? (  Question banks Downloads My Bookmarks Reviews Important topics
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Retired Moderator Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 175

Kudos [?]: 3037 , given: 394

If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? ( [#permalink]
Expert's post 00:00

Question Stats: 82% (00:29) correct 17% (00:54) wrong based on 29 sessions
If $$a\sharp b = a^2\sqrt{b} - a$$, where $$b ≥ 0$$, what is the value of $$(–4)\sharp 4$$?

(A) –36
(B) –28
(C) 12
(D) 28
(E) 36
[Reveal] Spoiler: OA

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Sandy
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Retired Moderator Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 175

Kudos [?]: 3037 , given: 394

Re: If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? ( [#permalink]
Expert's post
Explanation

This problem defines a function for the made-up symbol #.

In this problem a = (–4) and b = 4.

Plug the values into the function: $$(-4)^2 \sqrt{4}- (-4) = 16 \times 2 + 4 = 36$$.

Do not forget to keep the parentheses around the –4!

Also note that only the positive root of 4 applies, because the problem has been presented in the form of a real number underneath the square root sign.
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Sandy
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Founder  Joined: 18 Apr 2015
Posts: 13926
GRE 1: Q160 V160 Followers: 315

Kudos [?]: 3687 , given: 12942

Re: If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? ( [#permalink]
Expert's post
Intern Joined: 22 Oct 2019
Posts: 11
Followers: 0

Kudos [?]: 2 , given: 3

Re: If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? ( [#permalink]
sandy wrote:
Explanation

This problem defines a function for the made-up symbol #.

In this problem a = (–4) and b = 4.

Plug the values into the function: $$(-4)^2 \sqrt{4}- (-4) = 16 \times 2 + 4 = 36$$.

Do not forget to keep the parentheses around the –4!

Also note that only the positive root of 4 applies, because the problem has been presented in the form of a real number underneath the square root sign.
Founder  Joined: 18 Apr 2015
Posts: 13926
GRE 1: Q160 V160 Followers: 315

Kudos [?]: 3687 , given: 12942

Re: If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? ( [#permalink]
Expert's post Re: If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? (   [#permalink] 03 Nov 2020, 11:19
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# If a#b = a2 – a, where b ≥ 0, what is the value of (–4)#4? (  Question banks Downloads My Bookmarks Reviews Important topics  Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.