Question

Which term of AP: 5 , 2 , -1 , - 4,… is - 40 ?​

Answer 1

Answer:

a¹ =5

d = a²-a¹

d = 5-2 = 3

d = a³- a²

d = 2-(-1) = 2+1 = 3

an = a+(n-1) d

an= 5+ (n-1) *3

-40= 5+ 3n-3

-40 = 2+ 3n

3n = -42

n = -42/3

n = -14