Question

Please, please, please help me out with this!!!


Find the sum of the first six terms of the geometric sequence for which a2= 0.7 and a3= 0.49.

Answer 1

well the series is geometric based on the information

a general term is

\[a_{n} = a_{1} r^{n-1}\]

a1 = 1st term, r = common ratio

so start by finding the common ratio

2nd term
\[0.7 = ar\]

3rd term

\[0.49 = ar^2... or..... 0.49 = (ar) \times r ...or...... 0.49 = 0.7 \times r\]

so the common ratio is 0.7 and the 1st term is 1

then the you can use this information with n = 6 to find the sum

Answer 2

I got .16807 as my answer, is that correct, @raster?