Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

 It is currently 18 Jul 2019, 06:22

### 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

# Is √(x + y) an integer?

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

### Hide Tags

Senior Manager
Joined: 10 Mar 2013
Posts: 487
Location: Germany
Concentration: Finance, Entrepreneurship
Schools: WHU MBA"20 (A)
GMAT 1: 580 Q46 V24
GPA: 3.88
WE: Information Technology (Consulting)
Is √(x + y) an integer?  [#permalink]

### Show Tags

10 Dec 2015, 01:47
1
3
00:00

Difficulty:

25% (medium)

Question Stats:

76% (01:43) correct 24% (01:54) wrong based on 151 sessions

### HideShow timer Statistics

Is $$\sqrt{(x + y)}$$ an integer?

(1) $$x^3 = 64$$
(2) $$x^2 = y – 3$$

Source: Quant 700 to 800 level questions

_________________
When you’re up, your friends know who you are. When you’re down, you know who your friends are.

Share some Kudos, if my posts help you. Thank you !

800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50
GMAT PREP 670
MGMAT CAT 630
KAPLAN CAT 660
Senior Manager
Joined: 10 Mar 2013
Posts: 487
Location: Germany
Concentration: Finance, Entrepreneurship
Schools: WHU MBA"20 (A)
GMAT 1: 580 Q46 V24
GPA: 3.88
WE: Information Technology (Consulting)
Re: Is √(x + y) an integer?  [#permalink]

### Show Tags

10 Dec 2015, 02:13
BrainLab wrote:
Is $$\sqrt{(x + y)}$$ an integer?

(1) $$x^3 = 64$$
(2) $$x^2 = y – 3$$

Source: Quant 700 to 800 level questions

(1) Is clearly insufficient, as we don't have any Info about y
(2) Here I made a mistake firstly -> I set $$x^2 + 3 = y$$ in the expression and got $$\sqrt{(x^2 + x + 3)}$$. I thought, ok, it's a quadratic, so we can get some values for x and it should be sufficient. It was wrong to stop at that point. Discriminant for this expression < 0, which means there are no X-axis intersects.
For the parabola not to cross the x-axis, it must be that the parabola is always above the axis, so when is it greater than zero (above the axis)? Always! Solution: All X
It means that wwe just need to plugin some values for x, and test wheter we get an integer in any case.
It's an integer when x=2, but it is not an integer when x=1 NOT SUFFICIENT
(1) + (2) Sufficient: x=4, y=19, this expression doesn't yield an integer
Answer C
_________________
When you’re up, your friends know who you are. When you’re down, you know who your friends are.

Share some Kudos, if my posts help you. Thank you !

800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50
GMAT PREP 670
MGMAT CAT 630
KAPLAN CAT 660
Director
Joined: 20 Feb 2015
Posts: 790
Concentration: Strategy, General Management
Re: Is √(x + y) an integer?  [#permalink]

### Show Tags

10 Dec 2015, 23:47
1
statement one gives x =4 and no info on y so insufficient.
statement 2 is x^2=y-3 insufficient as various values can be plugged in
combining both
y=19
we therefore have root(23) which is not an integer so sufficient (C)
Senior Manager
Joined: 20 Aug 2015
Posts: 388
Location: India
GMAT 1: 760 Q50 V44
Is √(x + y) an integer?  [#permalink]

### Show Tags

11 Dec 2015, 04:17
BrainLab wrote:
Is $$\sqrt{(x + y)}$$ an integer?

(1) $$x^3 = 64$$
(2) $$x^2 = y – 3$$

Source: Quant 700 to 800 level questions

Required: $$\sqrt{(x + y)}$$ an integer?

Statement 1: $$x^3 = 64$$
This does not tell us anything about y.
INSUFFICIENT

Statement 2: $$x^2 = y – 3$$
We have one equation and two variables, hence this cannot be solved.
Also, we cannot bring down this equation in the required form
INSUFFICIENT

Combining Statement 1 and Statement 2:
From statement 1, we have x = 4
Substituting the value in $$x^2 = y – 3$$, 16 = y -3
y = 19
We have the values of x and y, hence we can find out $$\sqrt{(x + y)}$$

There is no need to solve for it, as we have just one set of values, hence only one possible answer
SUFFICIENT
Non-Human User
Joined: 09 Sep 2013
Posts: 11693
Re: Is √(x + y) an integer?  [#permalink]

### Show Tags

20 Aug 2018, 07:13
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Is √(x + y) an integer?   [#permalink] 20 Aug 2018, 07:13
Display posts from previous: Sort by

# Is √(x + y) an integer?

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

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