Question

Which one is the nth term if a1=15 and d= -3​

Answer 1

nth term = 18 - 3n

Explanation:

nth term = a + (n - 1)d

a1 = 15

d = -3

nth term = a + (n - 1)d

= 15 + (n - 1)-3

= 15 + (-3n + 3)

= 15 - 3n + 3

= 18 - 3n

nth term = 18 - 3n

For instance, if you want to find the 10th term

nth term = 18 - 3n

10th term = 18 - 3(10)

= 18 - 30

= -12

10th term = -12