Question

Question 15
If the first term of an AP is –5 and the common difference is 2, then the sum of the first 6 terms is

A) 0
B) 5
C) 6
D) 15

Answer 1

Given:
a = - 5
d = 2
$\therefore S_6=\frac{6}{2}[2a+(6-1\left)d\right][\because S_n=\frac{n}{2}\{2a+(n-1)d\left\}\right]$
$=3\left[2\right(-5)+5(2\left)\right]=3(-10+10)=0$