GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 13 Dec 2019, 13:31

Close

GMAT 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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 59721
If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what  [#permalink]

Show Tags

New post 25 Apr 2017, 03:14
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

83% (01:13) correct 17% (01:26) wrong based on 70 sessions

HideShow timer Statistics

Intern
Intern
avatar
B
Joined: 17 May 2016
Posts: 17
Re: If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what  [#permalink]

Show Tags

New post 25 Apr 2017, 03:50
xy/5 = 10x
y = 10 x 5 = 50

Sent from my HM NOTE 1LTE using Tapatalk
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2809
Re: If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what  [#permalink]

Show Tags

New post 28 Apr 2017, 15:16
1
1
Bunuel wrote:
If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what is the value of y?

(A) 0
(B) 5
(C) 25
(D) 50
(E) 5/x


We can FOIL the second expression (x – 5)^2 and equate the two expressions:

x^2 – xy/5 + 25 = x^2 -10x + 25

-xy/5 = -10x

-xy = -50x

y = 50

Answer: D
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Intern
Intern
avatar
B
Joined: 14 Apr 2017
Posts: 6
Re: If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what  [#permalink]

Show Tags

New post 21 May 2017, 22:19
Here y can take any value if x equals 0 and the question does not state that x is not equal to 0. In that consideration, shouldn't the answer be "Cannot be determined"? I think the answer should be D (i.e.: y=50) only if the question explicitly mentions that x does not equal 0.
Retired Moderator
avatar
P
Joined: 22 Aug 2013
Posts: 1409
Location: India
Re: If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what  [#permalink]

Show Tags

New post 21 May 2017, 22:30
mazhar7624 wrote:
Here y can take any value if x equals 0 and the question does not state that x is not equal to 0. In that consideration, shouldn't the answer be "Cannot be determined"? I think the answer should be D (i.e.: y=50) only if the question explicitly mentions that x does not equal 0.


But when it says x^2 - xy/5 + 25 = (x-5)^2

it means this expression is true for ALL values of x and y. So we have to generalise by the means of expanding (x-5)^2 and equating it with x^2 - xy/5 + 25
We cannot take a lone case of x=0.
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 15725
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what  [#permalink]

Show Tags

New post 30 Nov 2019, 12:30
Hi All,

We're told that X^2 - (X)(Y)/5 + 25 can be expressed as (X - 5)^2. We're asked for the value of Y. In simple terms, this question asks what value of Y will make the first expression be equal to the second expression.

(X - 5)^2 = X^2 - 10X + 25

Both the "X^2" and the "+25" are accounted for in the first expression, so we need -(X)(Y)/5 to equal - 10X....
thus Y/5 = 10
Y = 50

Final Answer:

GMAT assassins aren't born, they're made,
Rich
_________________
Contact Rich at: Rich.C@empowergmat.com
Image


The Course Used By GMAT Club Moderators To Earn 750+

souvik101990 Score: 760 Q50 V42 ★★★★★
ENGRTOMBA2018 Score: 750 Q49 V44 ★★★★★
GMAT Club Bot
Re: If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what   [#permalink] 30 Nov 2019, 12:30
Display posts from previous: Sort by

If the expression x^2 – xy/5 + 25 can be expressed by (x – 5)^2, what

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne