It is currently 26 Jun 2017, 06:57

### 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

# If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^

Author Message
Current Student
Joined: 28 Dec 2004
Posts: 3357
Location: New York City
Schools: Wharton'11 HBS'12
If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^ [#permalink]

### Show Tags

06 Sep 2005, 11:36
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.

If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^(x-2)) + y(a^(x-4)*b^(x-1)) + b^x, what is the value of yz?

(A) 24
(B) 30
(C) 36
(D) 42
(E) 50

Intern
Joined: 04 Sep 2005
Posts: 4
Re: If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^ [#permalink]

### Show Tags

06 Sep 2005, 12:20
The factors y & z follow the below shown triangle of values (can't remember its name):

1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1

For the equation given, y=5 & z =10...answer is 50
Current Student
Joined: 28 Dec 2004
Posts: 3357
Location: New York City
Schools: Wharton'11 HBS'12
Re: If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^ [#permalink]

### Show Tags

06 Sep 2005, 13:55
hmm could you shed some light on this?

I figured out what y is, but had hard time figuring z....

basically I know that x =5, then I know that the coefficient of y will also be 5....figuring out z is the hard part...

zag1979 wrote:
The factors y & z follow the below shown triangle of values (can't remember its name):

1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1

For the equation given, y=5 & z =10...answer is 50
Current Student
Joined: 28 Dec 2004
Posts: 3357
Location: New York City
Schools: Wharton'11 HBS'12
Re: If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^ [#permalink]

### Show Tags

06 Sep 2005, 13:57
actually this is a nice chart to remember whenever you have (a+b)^x...

depending on x..you can build out this chart...nice indeed....

can someone show how we can expand the pascal plot...to more than 6...
Manager
Joined: 06 Aug 2005
Posts: 197
Re: If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^ [#permalink]

### Show Tags

06 Sep 2005, 16:16
Just add the two numbers above each number when in the normal isosceles triangle design.

Or use the nCr formula.

Try looking up Pascal's triangle on a search engine on the internet.
Senior Manager
Joined: 15 Aug 2005
Posts: 257
Location: Las Vegas, NV
Re: If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^ [#permalink]

### Show Tags

06 Sep 2005, 22:09
zag1979 wrote:
The factors y & z follow the below shown triangle of values (can't remember its name):

1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1

For the equation given, y=5 & z =10...answer is 50

Zag! Pretty d@mn good! I totally forgot that from high school. That makes these kind of problems a piece of cake.
Re: If (a+b)^x=a^x + y(a^(x-1)*b^(x-4)) + z(a^(x-2)*b^(x-3)) + z(a^(x-3)*^   [#permalink] 06 Sep 2005, 22:09
Display posts from previous: Sort by