It is currently 17 Oct 2017, 05:15

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# What is the value of a^4 - b^4 ? 1) a^2 - b^2 = 16 2) a+b =

Author Message
Intern
Joined: 07 Dec 2006
Posts: 1

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

What is the value of a^4 - b^4 ? 1) a^2 - b^2 = 16 2) a+b = [#permalink]

### Show Tags

22 Dec 2006, 09:20
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

What is the value of a^4 - b^4 ?

1) a^2 - b^2 = 16
2) a+b = 8

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

Director
Joined: 17 Jul 2006
Posts: 702

Kudos [?]: 13 [0], given: 0

Re: help w/ GMAT Prep DS question [#permalink]

### Show Tags

22 Dec 2006, 09:57
dorilee6 wrote:
What is the value of a^4 - b^4 ?

1) a^2 - b^2 = 16
2) a+b = 8

1) a^2 - b^2= (a+b)(a-b)

2) a+b=8.

Using both 1 and 2 we know a-b=2.

using a+b and a-b values , we can find the value for a and b.

so a^4 - b^4 can be determined.

Kudos [?]: 13 [0], given: 0

Manager
Joined: 03 Jul 2005
Posts: 192

Kudos [?]: 12 [0], given: 0

Location: City

### Show Tags

22 Dec 2006, 14:14
What is the value of a^4 - b^4 ?

1) a^2 - b^2 = 16
2) a+b = 8

From A we canâ€™t tell what a or b is, could be any numero!
From B again we donâ€™t know what a or b is, could be any numbers 4.5 + 3.5 OR 7 + 1 etcâ€¦â€¦

Taking both statements together we can get 2 equations and work out the answer

1 = a^2 = 16 + b^2
2 = a = b â€“ 8

(b-8)(b-8) = 16 + b^2

b^2-16b+64 = 16 + b^2

16b = 48

B = 3

Voila!

Kudos [?]: 12 [0], given: 0

22 Dec 2006, 14:14
Display posts from previous: Sort by