Find the sums given below:
34 + 32 + 30 +….+10
The sum of the series given by
Sn =
[2a + (n-1) d]
Where n is the last term in the series
d is the common difference
a is the first term.
an = 10, a = 34
d = n2 – n1 = 32 - 34 = 2
an = a + (n-1)d
10 = 34 + (n-1)(-2)
-24 = -2(n-1)
12 = n-1
n = 13
The sum of the series is Sn =
[2a + (n-1) d]
=
[ 2×34 + (13-1)(-2)]
=
[ 44 ] ⇒ 286