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
--------------------------------------
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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