For the following A.P's write the first term and common difference:

- 3.1, - 3.0, - 2.9, - 2.8, ...

In general, for an AP a₁, a₂, . . . .,a_n, we have

d = a_k+1 - a_k

where a_k+1 and a_k are the (k+1)^th and k^th terms respectively.

For the list of numbers: - 3.1, - 3.0, - 2.9, - 2.8, ...

a₂ – a₁ = -3.0 – (-3.1) = -3.0 + 3.1 = 0.1

a₃ – a₂ = -2.9 – (-3.0) = -2.9 + 3.0 = 0.1

a₄ – a₃ = -2.8 – (-2.9) = -2.8 + 2.9 = 0.1

Here, the difference of any two consecutive terms in each case is 0.1. So, the given list is an AP whose first term a is -3.1 and common difference d is 0.1.