Question

for a gp if t3 is 20 and t6 is 160 find S
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Answer 1

Answer:

S7 = 635

Step-by-step explanation:

Let the first term of GP is a and common ration r

The third term of the GP

And the 6th term of the GP

Dividing the 6th term by the third term

or,  

Thus  

or, a = 5

Therefore, the sum upto 7 terms

\implies  

Hope this helps.

Step-by-step explanation: