VitalyCIB wrote:

Hi everyone!

I've come across this case in

Kaplan and still cannot understand, how to solve it in 1.5-2 minutes. Can anybody help?

\((2^3-1)(2^3+1)(2^6+1)(2^12+1)\)=

A. (2^24 -1)

B. (2^24 +1)

C. (2^48 -1)

D. (2^96 +1)

E. \(2^6\)(2^12 -1)

Hey

VitalyCIB, This question can be solved in just 20 seconds. Since U wrote "how to solve it in 1.5-2 minutes", it gave me a presumption in my mind that the question is going to be tough and hence I took 23 seconds..

So, lets start solving this question.

Formula required : \((x-y ) (x+y) = (x^2-y^2)\)

\((2^3-1)(2^3+1)(2^6+1)(2^{12}+1)\)

\(= ((2^3-1)(2^3+1))(2^6+1)(2^{12}+1)\)

\(= (2^6-1)(2^6+1)(2^{12}+1)\)

\(= ((2^6-1))(2^6+1))(2^{12}+1)\)

\(= (2^{12}-1)(2^{12}+1)\)

\(= (2^{24}-1)\)

Answer A Appreciation in the gmatclub format is always welcome..

_________________

CAT 99th percentiler : VA 97.27 | DI-LR 96.84 | QA 98.04 | OA 98.95

UPSC Aspirants : Get my app UPSC Important News Reader from Play store.

MBA Social Network : WebMaggu

Appreciate by Clicking +1 Kudos ( Lets be more generous friends.)

What I believe is : "Nothing is Impossible, Even Impossible says I'm Possible" : "Stay Hungry, Stay Foolish".