Monday, 3 July 2017

GEOM. PROGRESSION 1


The 1st term of a geometric progression is 7 and the 7th term is 448. Find the 8th term.

Solution

G1=7, G7=448, n=7

Gn = G1rn-1;

G7 = G1r7-1;

G7 = G1r6;

448 = 7 x r6;

448 = 7r6;
 7       7

64 = r6;  Finding the sixth root of 16,

r = 2

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Now the 8th term;

Gn = G1rn-1;

G8 = G1r8-1;

G8 = G1r7;  [G1 =7, r=2]

G8= 7 x 27;

G8 = 7 x 128;

Hence G8 =896

Hence the 8th term is 896.


TRY THIS………………………….. 


The 1st term of a geometric progression is 5 and the 6th term is 1215. Find the 14th term.   

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