help me out please

Question

A certain species of tree grows an average of 3.1 cm per week. Write an equation for the sequence that represents the weekly height of this tree in centimeters if the measurements begin when the tree is 400 centimeters tall.

Answer 1

Average growth rate = 3.1 cm/week.

So, common difference d = 3.1

The height of the tree a₀ = 400 centimeters.

The height of the tree after end of the first  week a₁ = 400 + 3.1 = 400 + 3.1(1)

The height of the tree after end of the second  week  a₂ = 400 + 3.1 + 3.1 = 400 + 3.1(2).

The height of the tree after end of the third  week a₃ = 400 + 3.1 + 3.1 + 3.1 = 400 + 3.1(3).

The height of the tree after end of the nth  week a_n =  400 + 3.1(n).

The equation is a_n = 400 + 3.1(n).