Question

sum of the first n terms of an arithmetic progression is n square + 4n . find the 15th term of the progression​

Answer 1

Answer:

solution : let n= 1

= 1+4(1)

=5

let n= 2

= 2+4(2)

= 2+6

= 8

let n= 3

= 3+4(3)

=3+12

= 15

let n = 15

= 15+4(15)

=15+60

=75

now : 5,8,15........…...75

the results is that the 15th term is 75