Question

Calculate sum of eleventh term of the geometric sequence $3,6,12,24,...$

• A. $3141$
• B. $6141$
• C. $2141$
• D. $5141$

Answer 1

The correct option is B $6141$

Given GP is $3,6,12,24,....$

Here first term $,a=3$ and common ratio $,r=2$
$S_n=\frac{a_1(r^n-1)}{r-1}$
$S_{11}=\frac{3\left(\right(2{)}^{11}-1)}{\left(2\right)-1}$
$=\frac{3\left(\right(2{)}^{11}-1)}{1}$
$=6141$