(Q19).Which of the following forms an AP? If they form an AP, then write the next two terms?

(i) x, 2x, 3x, 4x .....

We have a2 – a1 = – =

a3 – a2 = – =

a4 – a3 = – =

i.e., ak + 1 – ak is same every time

∴ So, the given list form an AP.

The next two terms are 4x + = and + = .