Question

find sum
of 13 terms of AP.
-6,0, 6, 12,
​

Answer 1

Answer:

No of terms= n = 13

First term = a = -6

difference= d= 6

sum= n(2a+(n-1)d)/2

= 13(-12+(12*6)/2

= 13(-12+72)/2

=13(60)/2

=13(30)

= 390