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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: If x and y are positive integers, what is the value of x^(1/2)+y^(1/2) [#permalink]

Show Tags

21 Oct 2015, 23:19

1

This post received KUDOS

((x)^(1/2)+(y)^(1/2))^2 = x + y + 2 *(xy)^(1/2)

1. x+y= 15 Not sufficient

2. (xy)^(1/2) = 6 Not sufficient

Combining 1 and 2, we get x + y + 2 *(xy)^(1/2)= 15 + 2*6=27 => ((x)^(1/2)+(y)^(1/2))^2 = 27 => (x)^(1/2)+(y)^(1/2) =3*((3)^(1/2)

Sufficient Answer C
_________________

When everything seems to be going against you, remember that the airplane takes off against the wind, not with it. - Henry Ford The Moment You Think About Giving Up, Think Of The Reason Why You Held On So Long +1 Kudos if you find this post helpful

If x and y are positive integers, what is the value of x^(1/2)+y^(1/2) [#permalink]

Show Tags

23 Oct 2015, 00:43

4

This post received KUDOS

Bunuel wrote:

If x and y are positive integers, what is the value of \(\sqrt{x} + \sqrt{y}\)?

(1) x + y = 15 (2) \(\sqrt{xy}= 6\)

Kudos for a correct solution.

1) Gives you various single values for x and y. Therefore clearly insufficient. 2) If \(\sqrt{xy}= 6\), then xy = 36 which can be built with 3*12 or 6*6 ... insufficient.

1+2) Here we know, x+y = 15 and xy = 36, hence x, or y are splitted up as 12 and 3. It does actually not matter if x is 3 or 12 or y is 3 or 12. The sum of \(\sqrt{x} + \sqrt{y}\) will be the same.

Answer C.
_________________

Saving was yesterday, heat up the gmatclub.forum's sentiment by spending KUDOS!

PS Please send me PM if I do not respond to your question within 24 hours.

Re: If x and y are positive integers, what is the value of x^(1/2)+y^(1/2) [#permalink]

Show Tags

23 Oct 2015, 05:42

2

This post received KUDOS

To find the value of \(\sqrt{x} + \sqrt{y}\) we need to know to have a value for x and a value for y.

Statement 1 : INSUFFICIENT x + y = 15 We have different possible values for x and y: x= 7 and y= 8 x= 9 and y= 6 x= 12 and y=3 All of these would yield different values for \(\sqrt{x} + \sqrt{y}\). Since we can't find a unique value, the statement is not sufficient.

Statement 2 : INSUFFICIENT If \(\sqrt{xy}=6\) then \((\sqrt{xy})^2=6^2\) and \(xy=\)36. Again, there are multiple values of x and y for which \(xy=36\): x=36 and y=1 x=6 and y=6 Since we can't find a unique value, the statement is not sufficient.

(1) + (2) = SUFFICIENT

We know that x+y = 15 and that xy=36, because x and y are positive integers we know that x=12 and y=3 OR x=3 and y=12 either way we will be able to calculate the value of \(\sqrt{x} + \sqrt{y}\) because it will not change the result.

If x and y are positive integers, what is the value of \(\sqrt{x} + \sqrt{y}\)?

(1) x + y = 15 (2) \(\sqrt{xy}= 6\)

Kudos for a correct solution.

Target question:What is the value of √x + √y?

Statement 1: x + y = 15 This statement doesn't FEEL sufficient, so I'll TEST some values. There are several values of x and y that satisfy statement 1. Here are two: Case a: x = 14 and y = 1, in which case √x + √y = √14 + √1 = √14 + 1 Case b: x = 9 and y = 6, in which case √x + √y = √9 + √6 = 3 + √6 Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: √(xy) = 6 In other words xy = 36 This statement doesn't FEEL sufficient either, so I'll TEST some values. There are several values of x and y that satisfy statement 2. Here are two: Case a: x = 1 and y = 36, in which case √x + √y = √1 + √36 = 1 + 6 = 7 Case b: x = 4 and y = 9, in which case √x + √y = √4 + √9 = 2 + 3 = 5 Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined Statement 1 tells us that x + y = 15 Statement 2 tells us that √(xy) = 6 Recognize that (√x + √y)² = x + 2√(xy) + y Rearrange to get: (√x + √y)² = 15 + 2(6) Evaluate: (√x + √y)² = 27 So, √x + √y = √27 Since we can answer the target question with certainty, the combined statements are SUFFICIENT