Question

if the first term of AP is 2 and common difference is 4 , then the sum of first 40 terms is​

Answer 1

a = 2, d = 4, n = 40

From the formula

Sn= n/2[2a+(n-1)d]}

S{40}= 40/2[2(2)+(40-1)4]

S_{40}= 20[4+(39)4]

S_{40}= 20[4+156]

S_{40}= 20[160]

S_{40}= 3200

the sum of first 40 terms is 3200