Question

In an arithmetic progression of n terms, the common differences is d and the last terms is l. How to find first two terms of the A.P in terms of d, l and n?

Answer 1

First two terms are `l-(n-1)d` and `l-(n-2)d`

Explanation:

Let the first term be `a` and as common diference is `d` and `n^(th)` term is `l`, we have

`l=a+(n-1)d`

aand hence `a=l-(n-1)d`

and second term is `l-(n-1)d+d=l-(n-2)d`