# Math

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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 -

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 -

If 10th term of a G.P. Is 9 and fourth term is 4, then its 7th term is:

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