R redpint New Member Joined Sep 16, 2012 Messages 18 Gender Female HSC 2013 Nov 19, 2012 #1 hi everyone, how would you do this question? Evaluate the sum of the first 20 terms of the series 5 - 2 + 10 - 8 + 15 - 32 ... Thanks!
hi everyone, how would you do this question? Evaluate the sum of the first 20 terms of the series 5 - 2 + 10 - 8 + 15 - 32 ... Thanks!
M michaeljennings Active Member Joined Oct 11, 2009 Messages 2,075 Location Sydney Gender Male HSC 2011 Nov 19, 2012 #2 Split this up into an AP and GP AP: 5, 10, 15 ... GP: -2, -8, -32 ... Then evaluate the sum of the first 10 terms for the AP and then the sum of the first 10 terms for the GP and thats the sum of the first 20 terms of your original series
Split this up into an AP and GP AP: 5, 10, 15 ... GP: -2, -8, -32 ... Then evaluate the sum of the first 10 terms for the AP and then the sum of the first 10 terms for the GP and thats the sum of the first 20 terms of your original series
