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.
If k is a two-digit positive integer with tens digit x and units digit
[#permalink]
12 Sep 2023, 04:15
12 Sep 2023, 04:15
Expert Reply
00:00
Question Stats:
80% (02:18) correct
20% (02:50) wrong based on 10 sessions
Hide Show timer Statistics
If k is a two-digit positive integer with tens digit x and units digit y, then \(k^2 −(x+y)^2\) must be divisible by which of the following?
(A) 2
(B) 6y
(C) 9x
(D) 9xy
(E) 27
(A) 2
(B) 6y
(C) 9x
(D) 9xy
(E) 27
Part of the project: The Butler-GRE Daily New Quant and Verbal Questions to Practice (2023) - Gain 20 Kudos & Get FREE Access to GRE Prep Club TESTS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Free Materials for the GRE General Exam - Where to get it!!
GRE Geometry Formulas
GRE - Math Book
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Free Materials for the GRE General Exam - Where to get it!!
GRE Geometry Formulas
GRE - Math Book
Re: If k is a two-digit positive integer with tens digit x and units digit
[#permalink]
15 Sep 2023, 14:10
15 Sep 2023, 14:10
1
10x + y = k
k^2 - (x+y)^2
(10x+y)^2 - (x+y)^2
Property:
x^2 - y^2 = (x+y)(x-y)
Apply the property to the question:
(10x+y)^2 - (x+y)^2 = (10x+y+x+y)(10x+y-x-y) = (11x + 2y)(9x)
This means k^2 - (x+y)^2 is divisible by 9x. Choice C.
k^2 - (x+y)^2
(10x+y)^2 - (x+y)^2
Property:
x^2 - y^2 = (x+y)(x-y)
Apply the property to the question:
(10x+y)^2 - (x+y)^2 = (10x+y+x+y)(10x+y-x-y) = (11x + 2y)(9x)
This means k^2 - (x+y)^2 is divisible by 9x. Choice C.
gmatclubot
Re: If k is a two-digit positive integer with tens digit x and units digit [#permalink]
15 Sep 2023, 14:10
Moderators:
