Friday 20 December 2013

SEQUENCE AND SERIES A8

Find the sum of the 1st eight terms of the geometrical progression 2+4+8+16+…….

solution

G1 = 2, r=2, n=8

Sn = G1(rn-1)/r-1
               

S8 = 2(28-1)/2-1
             

S8 = 2(28-1)/1
              

S8 = 2(28-1)

S8 = 2(256-1)

S8 = 2(255)

S8 = 510


Hence the sum of the 1st eight terms is 510.

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