Find the sum :

2 + 7 + 12 + 17 + ….. to 19 terms.

The above sequence is an A.P. with common difference = 12 - 7 = 5.

We know that,

Sum of n terms of an A.P. is given by,

∴ S_n = $\dfrac{n}{2}$ [2a + (n - 1)d]

⇒ S₁₉ = $\dfrac{19}{2}$ [2(2) + (19 - 1)5]

= 9.5 [4 + (18)5]

= 9.5 [4 + 90]

= 9.5 (94)

= 893.

Hence, S₁₉ = 893.