Find all School-related info fast with the new School-Specific MBA Forum

It is currently 23 Oct 2014, 00:20

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Elimination of radials - Confused¿?

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 15 Aug 2011
Posts: 4
Followers: 0

Kudos [?]: 1 [0], given: 0

Elimination of radials - Confused¿? [#permalink] New post 05 Sep 2012, 09:12
Actually the question is pretty straight forward, however upon further examination I somehow got confused on the "well-known" fact that anything you do to one side of an algebraic equation, you must do to the other side. I'll try to elaborate with an example:

Given that √(3b-8) = √(12-b), what is b?

I understand that the approach is to cancel both radicals, and then just proceed with a very simple equation. However in strict theory, wouldn't you have to multiply what you do to one side, to the other side as well?

√(3b-8)^2 = √(12-b) * √(3b-8)

I know I am completely wrong, but it is probably only a matter of having too much of this GMAT stuff.
Thanks to anyone that will kindly respond to my inquiry.
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesManhattan GMAT Discount Codes
Director
Director
User avatar
Joined: 22 Mar 2011
Posts: 612
WE: Science (Education)
Followers: 73

Kudos [?]: 529 [0], given: 43

Re: Elimination of radials - Confused¿? [#permalink] New post 05 Sep 2012, 14:14
Patheinemann wrote:
Actually the question is pretty straight forward, however upon further examination I somehow got confused on the "well-known" fact that anything you do to one side of an algebraic equation, you must do to the other side. I'll try to elaborate with an example:

Given that √(3b-8) = √(12-b), what is b?

I understand that the approach is to cancel both radicals, and then just proceed with a very simple equation. However in strict theory, wouldn't you have to multiply what you do to one side, to the other side as well?

√(3b-8)^2 = √(12-b) * √(3b-8)


I know I am completely wrong, but it is probably only a matter of having too much of this GMAT stuff.
Thanks to anyone that will kindly respond to my inquiry.


An equality, you can also raise to some power.
If for two non-zero numbers A=B, then multiplying both sides by A we obtain A\cdot{A}=AB but A=B, so A^2=B^2. You can continue and obtain that for any positive integer n, \, A^n=B^n.

What you have written is true, but it won't help you get rid of the radicals the way it is written.

If two numbers are equal, raised to the same power will remain equal. You do the same to both sides of the equation, you raise them to the second power.
_________________

PhD in Applied Mathematics
Love GMAT Quant questions and running.

Expert Post
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4877
Location: Pune, India
Followers: 1153

Kudos [?]: 5366 [0], given: 165

Re: Elimination of radials - Confused¿? [#permalink] New post 07 Sep 2012, 21:19
Expert's post
Patheinemann wrote:
Actually the question is pretty straight forward, however upon further examination I somehow got confused on the "well-known" fact that anything you do to one side of an algebraic equation, you must do to the other side. I'll try to elaborate with an example:

Given that √(3b-8) = √(12-b), what is b?

I understand that the approach is to cancel both radicals, and then just proceed with a very simple equation. However in strict theory, wouldn't you have to multiply what you do to one side, to the other side as well?

√(3b-8)^2 = √(12-b) * √(3b-8)

I know I am completely wrong, but it is probably only a matter of having too much of this GMAT stuff.
Thanks to anyone that will kindly respond to my inquiry.


Take some numbers to understand this.
The equality sign means that whatever is on the left hand side, it is equal to whatever there is on the right hand side. So if the LHS is 2, RHS is also 2

2 = 2
Now, you can square both sides and the equality will still hold 2^2 = 2^2
You can raise both sides to any power, the equality will hold.

You can also multiply the same number on both the sides, the inequality will still hold 2*3 = 2*3

You can choose to do whichever operation suits your purpose. Since you want to get rid of the root sign, you would want to square both sides.

Also, notice that here √(3b-8)^2 = √(12-b) * √(3b-8),
√(3b-8) = √(12-b) (even though they don't look same but they are since it is given to us) so √(3b-8)^2 = √(12-b) * √(3b-8) is the same as √(3b-8)^2 = √(12-b)*√(12-b)
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Manager
Manager
avatar
Joined: 24 Jul 2011
Posts: 77
Location: India
Concentration: Strategy, General Management
GMAT 1: 670 Q49 V33
WE: Asset Management (Manufacturing)
Followers: 2

Kudos [?]: 63 [0], given: 5

Re: Elimination of radials - Confused¿? [#permalink] New post 09 Sep 2012, 07:45
Patheinemann wrote:
Actually the question is pretty straight forward, however upon further examination I somehow got confused on the "well-known" fact that anything you do to one side of an algebraic equation, you must do to the other side. I'll try to elaborate with an example:

Given that √(3b-8) = √(12-b), what is b?

I understand that the approach is to cancel both radicals, and then just proceed with a very simple equation. However in strict theory, wouldn't you have to multiply what you do to one side, to the other side as well?

√(3b-8)^2 = √(12-b) * √(3b-8)

I know I am completely wrong, but it is probably only a matter of having too much of this GMAT stuff.
Thanks to anyone that will kindly respond to my inquiry.


For such question to solve, firstly try to form simple equation. For this we need to get out of that square root.
Now, if a=b, then a^2 = b^2(squaring both sides)
In our case,
\sqrt{(3b-8)}^2 = \sqrt{(12-b)}^2
-->> 3b-8=12-b
-->> 4b=24
-->> b=24/4=6
Therefore, b=6
_________________

My mantra for cracking GMAT:
Everyone has inborn talent, however those who complement it with hard work we call them 'talented'.


+1 Kudos = Thank You Dear :)
Are you saying thank you?

Re: Elimination of radials - Confused¿?   [#permalink] 09 Sep 2012, 07:45
    Similar topics Author Replies Last post
Similar
Topics:
2 Eliminating properties qweert 3 23 Aug 2010, 05:29
Confusing... somethingbetter 0 06 Jul 2007, 14:29
confused Nuray 5 24 Sep 2006, 17:27
Confused need700+ 7 19 Aug 2005, 11:00
Experts publish their posts in the topic Confused just4fun 3 06 Dec 2004, 02:47
Display posts from previous: Sort by

Elimination of radials - Confused¿?

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.