Last visit was: 19 Dec 2024, 22:33 It is currently 19 Dec 2024, 22:33

Close

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

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 GRE 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
Verbal Expert
Joined: 18 Apr 2015
Posts: 30412
Own Kudos [?]: 36769 [14]
Given Kudos: 26087
Send PM
Most Helpful Community Reply
avatar
Director
Director
Joined: 03 Sep 2017
Posts: 518
Own Kudos [?]: 707 [6]
Given Kudos: 0
Send PM
General Discussion
avatar
Intern
Intern
Joined: 11 Jan 2018
Posts: 44
Own Kudos [?]: 104 [4]
Given Kudos: 0
Send PM
User avatar
Manager
Manager
Joined: 26 Jun 2017
Posts: 102
Own Kudos [?]: 71 [0]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
so
Attachments

5656565.jpg
5656565.jpg [ 131.56 KiB | Viewed 15986 times ]

Verbal Expert
Joined: 18 Apr 2015
Posts: 30412
Own Kudos [?]: 36769 [0]
Given Kudos: 26087
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
Expert Reply
Please boxing,

your replies are very delightful. However, please as a test and not as a screenshot.

Thank you so much for your collaboration. The board is cleaner that way.

regards
avatar
Manager
Manager
Joined: 28 Nov 2017
Posts: 56
Own Kudos [?]: 82 [2]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
2
Short & Quick way to get the Answer is :

3x has to be less than 10 as we can't find out the Sqaure root of a a negative number so x can only take values of 0,1,2 & exclude non negative solutions so 2 is rejected. Answer b
avatar
Manager
Manager
Joined: 22 Feb 2018
Posts: 163
Own Kudos [?]: 215 [2]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
2
Answer: B
Sure root of 10 - 3x is greater than x and x is a non-negative integer.
First, as x is non-negative, thus |x| equals x in A.
We try numbers. The minimum value for x can be 0.
If x = 0, square root of 10-3x equals 10, which is greater than x.
If x = 1, 10-3 is greater than 1
If x = 2, 10- 6 is not greater than 2.
So, x can be either 0 or 1 and always less than 2.
The answer is B.
avatar
Intern
Intern
Joined: 20 Mar 2018
Posts: 39
Own Kudos [?]: 129 [0]
Given Kudos: 0
GRE 1: Q163 V149

GRE 2: Q168 V162
GPA: 3.5
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
Yiddo_Bhushan wrote:
Short & Quick way to get the Answer is :

3x has to be less than 10 as we can't find out the Sqaure root of a a negative number so x can only take values of 0,1,2 & exclude non negative solutions so 2 is rejected. Answer b


However, it is not mentioned that x has to be an integer. x can be just less than 10/3 or 3 for that matter.
avatar
Intern
Intern
Joined: 20 Mar 2018
Posts: 39
Own Kudos [?]: 129 [0]
Given Kudos: 0
GRE 1: Q163 V149

GRE 2: Q168 V162
GPA: 3.5
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
1
Given: x>0
and
\sqrt{(10-3x)} > x gives -5<x<2

Ignoring negative solutions. 0<x<2 and |x| would be less than 2
avatar
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
Hey guys, I understand your solution, but could you point out the fallacy or mistake in my solution.

sqrt(10-3x) > x
x>=0 so sqrt(10-3x)>0
then 10-3x >0
Thus x < (10/3)

So D because the absolute value of x can be greater than 2 or smaller than 2.
avatar
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
IlCreatore wrote:
We need to solve the equation \(sqrt(10-3x)>x\). Squaring both sides we get \(10-3x>x^2\) that can be rewritten as \(x^2+3x-10<0\). The left hand side can be rewritten as \((x-5)(x+2)\), thus the solution of the equation is \(-5<x<2\).

Since x is non negative, among the solutions we must consider only those between 0 and 2, excluded. Thus, no matter the absolute value, column A is always smaller than 2.

Answer B


Perhaps it is a simple typo, but what you should have (x+5)(x-2) as the factor, then it would mean that -5>x>2.
avatar
Supreme Moderator
Joined: 01 Nov 2017
Posts: 371
Own Kudos [?]: 471 [0]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
1
Expert Reply
QuantumWonder wrote:
Hey guys, I understand your solution, but could you point out the fallacy or mistake in my solution.

sqrt(10-3x) > x
x>=0 so sqrt(10-3x)>0
then 10-3x >0
Thus x < (10/3)

So D because the absolute value of x can be greater than 2 or smaller than 2.



You are wrong in replacing X with 0.
\(\sqrt{10-3x}>x\)..
So the LHS and RHS are interconnected, as increase in X will increase both sides ..

You cannot simply replace X with 0...
That would ok if you were simply finding out if some term is negative or positive
avatar
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [3]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 – 3x) [#permalink]
3
Okay, here is a solution that is purely algebraic ( boxing has a mistake in inequality direction).

sqrt (10-3x) > x
10-3x > x^2
0 > x^2 + 3x - 10
x^2 + 3x - 10 < 0
(x+5)(x-2) < 0

There are two options, x+5 < 0 and x- 2 > 0 || or || x+5 > 0 & x-2< 0
Why? Because each option, when multiplied, would still give you a negative.
First option: x< -5 and x > 2, x is nonnegative so you can throw out first inequality out. For the second inequality, plug this in the criteria 10-3x>x^2 and you will see it doesn't work. Thus, throw it out as well.
Second option: x>-5 and x<2, again, here we throw out the negative solution x>-5.

So x < 2.

Thus B.
User avatar
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 5084
Own Kudos [?]: 76 [0]
Given Kudos: 0
Send PM
Re: x is a non-negative number and the square root of (10 3x) [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep 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.
Prep Club for GRE Bot
Re: x is a non-negative number and the square root of (10 3x) [#permalink]
Moderators:
GRE Instructor
88 posts
GRE Forum Moderator
37 posts
Moderator
1115 posts
GRE Instructor
234 posts

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