Tuesday 17 December 2013

SEQUENCE AND SERIES A1

The 1st term of a geometric progression is 6 and the 4th term is 48. Find the common ratio.

solution

G1=6, G4=48, n=4

Gn = G1rn-1;

G4 = G1r4-1;

G4 = G1r3;

48 = 6 x r4-1;

48 = 6 x r3;

48 = 6r3;
 6     6

8 = r3;  Finding the cube root of 8,

r = 2


Hence the common ratio is 2.

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