gmat prep cubed

This topic has expert replies
Source: — Problem Solving |

Junior | Next Rank: 30 Posts
Posts: 12
Joined: Mon Jan 21, 2008 11:12 pm

by jscoligan » Tue May 06, 2008 3:06 pm
Viper, you gotta cube both sides (it's testing the multiplication of exponents), after cubing both sides you get x-b=c^18, then add b to both sides.

User avatar
GMAT Instructor
Posts: 85
Joined: Thu May 01, 2008 12:56 pm
Location: Salt Lake City, UT
Thanked: 24 times
GMAT Score:750+

by VP_RedSoxFan » Tue May 06, 2008 5:42 pm
Just to follow up, when you raise a term with an exponent, to an exponent, you can multiple the exponents:

(x^a)^b = x^(a*b)

As was mentioned, this question is testing your knowledge of properties of exponents. Contrast this with multiplying terms raised to exponents:

x^a * x^b = x^(a+b)
Ryan S.
| GMAT Instructor |
Elite GMAT Preparation and Admissions Consulting
www.VeritasPrep.com

Learn more about me

Master | Next Rank: 500 Posts
Posts: 468
Joined: Sat Mar 03, 2007 10:17 pm
Thanked: 5 times

by moneyman » Wed May 07, 2008 5:09 am
Just to clear out things...Can the left hand side of the expression be written as (x-b)^1/3 ?? This is because sq.rt(x-b)=(x-b)^1/2 so can we do the same thing for cube root??
Maxx

User avatar
GMAT Instructor
Posts: 85
Joined: Thu May 01, 2008 12:56 pm
Location: Salt Lake City, UT
Thanked: 24 times
GMAT Score:750+

by VP_RedSoxFan » Wed May 07, 2008 7:35 am
That's right. When you take nth roots, it is the same as raising to a 1/n power.
Ryan S.
| GMAT Instructor |
Elite GMAT Preparation and Admissions Consulting
www.VeritasPrep.com

Learn more about me

Master | Next Rank: 500 Posts
Posts: 222
Joined: Tue Mar 25, 2008 3:52 pm
Thanked: 2 times

by vinviper1 » Thu May 08, 2008 1:29 pm
Ahhh....not too hard when you plan it out. Thank you guys.