The first term of an A.P is 2, and common difference is 4, the sum of its 40 terms will be

The first term of an A.P is 2, and common difference is 4, the sum of its 40 terms will be
a) 3200
b) 1600
c) 200
d) 2800

Answer is 3200.
Given :
First term,(a) = 2 , common Difference ,d = 4 , n = 40

By using the formula ,Sum of nth terms , Sn = n/2 [2a + (n – 1) d]

S40 = 40/2 [2 x 2 + (40 - 1) 4]
S40 = 20 [4 + 39 × 4]
S40 = 20 (4 + 156)
S40 = 20 × 160
S40 = 3200
Hence, the sum of its 40 terms is 3200.