Question

In AP find 4 + 7 + 10 + 13 + 16 + ... upto 20 terms

विकल्प

• 750

• 854

• 650

• 740

Answer 1

650
Explanation:
Here, a = 4
d = 7 - 4 = 3
Sum of first 20 terms,
S_n = `n/2` [2a + (n - 1) d]
S₂₀ = `20/2` [(2 x 4) + (20 - 1) 3]
= 10[8 + (19 x 3)]
= 10(8 + 57) = 650