Posted by **Malek** on Saturday, January 15, 2011 at 6:45am.

the sum of the 4th term and the 5th term is 12.if the 4th term of the progression is 8, find the common ratio and the 1st term of the progression.

- Math -
**drwls**, Saturday, January 15, 2011 at 7:27am
Call the first term A1.

The An term is A1*r(n-1)

A4 = 8

A4 + A5 = 12 so A5 = 4 and r = 1/2 is the ratio.

Since A4 = 8, A1 = 64 is the first term

The series progression is

64, 32, 16, 8, 4, 2,...

- Math -
**Anonymous**, Tuesday, December 18, 2012 at 2:59am
If 10th term of a G.P. Is 9 and fourth term is 4, then its 7th term is:

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