Question

Please help! I am supposed to write a recursive and an explicit function for the geometric sequence but this one is really frustrating me. Thank you!

Answer 1

Step-by-step explanation:

Initially, there's only 1 letter.

Tania sends the letter to 4 friends.

Each friend sends a letter to 4 more friends (4 × 4 = 16).

Each of those friends sends to 4 more friends (16 × 4 = 64).

The pattern is 1, 4, 16, 64, etc.

This is a geometric sequence.  The first term is 1 and each term is 4 times the previous term.

a₁ = 1

aₙ = 4 aₙ₋₁

The explicit formula is:

aₙ = 1 (4)ⁿ⁻¹