GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
GRE Prep Club Team Member
Joined: 20 Feb 2017
Posts: 2508
Given Kudos: 1051
GPA: 3.39
For all numbers x and y the definition of the operation
[#permalink]
08 Feb 2020, 05:51
08 Feb 2020, 05:51
1
Expert Reply
00:00
Question Stats:
90% (00:55) correct
9% (01:12) wrong based on 33 sessions
Hide Show timer Statistics
For all numbers \(x\) and \(y\) the definition of the operation \(♦\) is \(x♦ y=xy(x+4)\). If \((-6) ♦ a = -60,\) then what is the value of \(a\) ?
A. -20
B. -5
C. 2.5
D. 5
E. 10
A. -20
B. -5
C. 2.5
D. 5
E. 10
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: For all numbers x and y the definition of the operation
[#permalink]
08 Feb 2020, 06:42
08 Feb 2020, 06:42
1
GeminiHeat wrote:
For all numbers \(x\) and \(y\) the definition of the operation \(♦\) is \(x♦ y=xy(x+4)\). If \((-6) ♦ a = -60,\) then what is the value of \(a\) ?
A. -20
B. -5
C. 2.5
D. 5
E. 10
A. -20
B. -5
C. 2.5
D. 5
E. 10
Given: \(x♦y=xy(x+4)\)
So: \((-6)♦a=(-6)(a)[(-6)+4]\)
Simplify to get: \((-6)♦a=(-6)(a)(-2)\)
Simplify again to get: \((-6)♦a=12a\)
We are also told that: \((-6) ♦ a = -60,\)
This means we can write: \(12a =-60\)
Divide both sides by 12 to get: \(a =-5\)
Answer: B
Cheers,
Brent
GRE Instructor
Joined: 19 Jan 2020
Status:Entrepreneur | GMAT, GRE, CAT, SAT, ACT coach & mentor | Founder @CUBIX | Edu-consulting | Content creator
Posts: 117
Given Kudos: 0
GPA: 3.72
Re: For all numbers x and y the definition of the operation
[#permalink]
09 Feb 2020, 09:13
09 Feb 2020, 09:13
2
GeminiHeat wrote:
For all numbers \(x\) and \(y\) the definition of the operation \(♦\) is \(x♦ y=xy(x+4)\). If \((-6) ♦ a = -60,\) then what is the value of \(a\) ?
A. -20
B. -5
C. 2.5
D. 5
E. 10
A. -20
B. -5
C. 2.5
D. 5
E. 10
We know that: \(x♦ y=xy(x+4)\)
Thus: \((-6) ♦ a = -60\)
\(=>(-6)(a)(-6+4) = -60\)
\(=>12a = -60\)
\(=>a = -5\)
Answer B
