Question

find the sum of nth term of ap whose kth term is 5k+1

Answer 1

We know that nth term of an AP = a + (n - 1) * d.

Given kth term of an AP ak = 5k + 1.

Substitute k = 1, we get

= > a1 = 5(1) + 1

= 6.

= > a2 = 5(2) + 1

= 11.

Common difference d = a2 - a1

= > 11 - 6

= > 5.

Now,

We know that sum of n terms of an AP sn = (n/2)[2a + (n - 1) * d]

= > (n/2)[2(6) + (n - 1) * 5]

= > (n/2)[12 + 5n - 5]

= > (n/2)[5n + 7].

Hope this helps!

Answer 2

Step-by-step explanation:

step 1 -Find a and d

step2 -put values of a and d in Sn