Question

Write fourth term of an AP when the frist term is 4 and the common difterence is -3.​

Answer 1

Answer:

Let d be the common difference. The sum of the first 12 terms is then

4+(4+d)+(4+2d)+ ... +(4+11d)

Recall now the key fact that the sum of the first n integers is (n+1)n2. Obviously you can write the expression for the sum of the first 8 terms similarly and it should now reduce just to arithmetic.....................