Question

In an arithmetic series, if S7=56, and d=5, then how do you find A1?

Answer 1

`a_1 = 26`

Explanation:

We know that in an AP, `n^(th)` term is given by
`a_n= a_1 + (n – 1)d`
where `a_1` is the first term and `d` is common difference.

Given `a_7=56 and d=5`, substituting in the general expression and solving for `a_1`
`56= a_1 + (7 – 1)5`
`a_1 = 26`