Question

Which term of the ap 4,12,20,28... Will be 120 more than its 21st term?

Answer 1

Answer:

36th term

Step-by-step explanation:

tₙ = a + (n-1)d

a=4, d = 8.

21st term is

t₂₁ = 4 + (21-1)8 = 164.

So the number that is 120 more than 21st term = 164 + 120 = 284.

284 = 4 + (n-1)8

=> (n-1)8 = 280

-> n - 1 = 35

=> n = 36.

Thus the term is 36th term.