Question
Wed March 06, 2013 By:

see below

Expert Reply
Wed March 06, 2013

Sq = 63q - 3q2

Therefore,

S1 = 63(1) - 3(1)2 = 60 = a 1

S2 = 63(2) - 3(2)2 = 126 - 12 = 114

and so on

We get, a 1 = 60

a2 = S2 - S1 = 114 - 60 = 54

Therefore, AP is 60, 54, 48, .......

a = 60 , d = -6

ap = a+(p-1)d

-60 = 60 - 6p + 6

-60 = 66 - 6p

-126 = -6p

p = 21

a11 = a+10d = 60 + 10(-6)  = 60 - 60 = 0

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