Question

Find the sum of the given geometric series: $n=10,r=-1$, $a_1=1$

• A. $0$
• B. $1$
• C. $2$
• D. $3$

Answer 1

The correct option is A $0$

Given, $n=10,r=-1,a_1=1$

Sum of a GP $=\frac{a(r^n-1)}{r-1}$

Therefore, $\text{sum}=\frac{1\left(\right(-1{)}^{10}-1)}{-1-1}$

$\Rightarrow \text{sum}=\frac{1-1}{-2}$

$\Rightarrow \text{sum}=0$