# series doubt

• Aug 17th 2009, 09:32 AM
bluffmaster.roy.007
series doubt
Given a sequence a1, a2........ an. If a1 = 25 & in the sequence if every number is '-2' times the preceding number,

then Col A: a100 Col B: -10,000 which of both are great ..i did for a100 as 25(-2^99) so Col is bigger is it correct
• Aug 17th 2009, 11:18 AM
CaptainBlack
Quote:

Originally Posted by bluffmaster.roy.007
Given a sequence a1, a2........ an. If a1 = 25 & in the sequence if every number is '-2' times the preceding number,

then Col A: a100 Col B: -10,000 which of both are great ..i did for a100 as 25(-2^99) so Col is bigger is it correct

Since $25\times (-2)^{99} \approx -1.6 \times 10^{31} < -10000$

CB