Question

the nth term of an AP is the difference of the sum to furst n terms and the sum to first n-1 term of it ie a_n=S_n-S_n-1
Can anyone explain this
That why this happens

Answer 1

Answer:

,

Step-by-step explanation:

refer to the attachment

Answer 2

Answer:

I also want to find its answer but can't find it's answer.