45. Exemplar exercise problem IV

1. The first term of an AP is \(–5\) and the last term is \(45\). If the sum of the terms of the AP is \(120\), then find the number of terms and the common difference.

 

The common difference \(d =\) .

The number of terms of an A.P. \(n =\) .

 

 

2. Which term of the AP: \(–2, –7, –12,...\) will be \(–77\)? Find the sum of this AP upto the term \(–77\).

 

The term \(-77\) be th term.

The sum of the given sequence is .