Question

If the first term of an ap is -5 and c. D is 2 then the sum of the first 6 term is

Answer 1

1st term, a = -5
c.d = 2
sum of 6terms = 6/2{2*(-5)+(6-1)2}
=3{-10+10}
=3*0
=0

Answer 2

Here,
a=-5
C.D=2
n=6

$we \: know \: that \\ sum \: f \: ap \: \\ = \frac{n}{2} (2a + (n - 1)d) \\ = \frac{6}{2} (2 \times - 5 + (6 - 1)2) \\ = 3( - 10 + 5 \times 2) \\ = 3( - 10 + 10) \\ = 3 \times 0 \\ = 0$
Hence the sum of first 6term is 0