Question

Write the formula for sum of first k terms by an AP with first term ‘a’ and common

difference ‘d’. (Write in both forms)​

Answer 1

Answer:

Correct option is

A

a=2d

Given, first term =a, common difference =d

By using Sn=2n[2a+(n−1)d] we have,

∴SxSkx=2x(2a+(x+1)d)2kx(2a+(kx−1)d)

⇒SxSkx=(2a+(x+1)d)k(2a+(kx−1)d)

⇒SxSkx=2a+xd−dk(2a−d+kxd)

Now this will be independent of x only when 2a=d or a=2d

Answer 2

Answer:

sorry... I don't know how to solve