Question

Find the partial sum S7 for the geometric sequence with a=3,r=2.S7=

Answer 1

The formula for the partial sum of a geometric sequence is given by:

`S_n=(a(r^n-1))/(r-1)`

From the problem, we identify:

`\begin{gathered} n=7 \\ a=3 \\ r=2 \end{gathered}`

Finally, using these values in the formula:

`\begin{gathered} S_7=(3(2^7-1))/(2-1)=(3(128-1))/(1)=3\cdot127 \\ \\ \therefore S_7=381 \end{gathered}`