Question

Find the sum of ap 40+37+35+........+(-107)

Answer 1

a = 40
d = 37 - 40 = -3
An or l = -107

An = a + (n - 1)d
-107 = 40 + (n - 1)* -3
-107 -40 = - 3n + 3
-147 - 3 = -3n
-150/-3 = n
n = 50

Sn = n/2(a + l)
Sn = 50/2 (40 + -107)
Sn = 25 (-67)
Sn = - 1675


Sum of the AP is -1675