Can you tell me the 4th terms in the sequence? f(1) = 15, f(n) = f(n-1) - 10

Answer 1

f(1) = 15 (given)

f(2) = f(2 - 1) - 10 = f(1) - 10 = 15 - 10 = 5

f(3) = f(3 - 1) - 10 = f(2) - 10 = 5 - 10 = -5

f(4) = f(4 - 1) - 10 = f(3) - 10 = -5 - 10 = -15

This is equivalent to an arithmetic sequence with 1st term = 15, difference of -10.

a_n = a₁ + (n - 1)d a₁ = 15, n = 4, d = -10, a_n = nth term in the sequence

a_n = 15 + (4 - 1)(-10) → 15 + (3)(-10) → 15 + (-30) = -15

Answer 2

Understanding the notation is very important f(n-1) represents the previous term. Watch the video to get the complete explanation