Thursday 19 December 2013

SEQUENCE AND SERIES A4

Find the sum of the 1st eight terms of the geometrical progression 3+6+12+24+…….

Solution

G1 = 3, r=2, n=8

Sn = G1(rn-1)/r-1
               

S8 = 3(28-1)/ 2-1
            

S8 = 3(28-1)

S8 = 3(256-1)

S8 = 3(255)

S8 = 765



Hence the sum of the 1st eight terms is 765.

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