A conservationist is tracking the number of a rare type of tree in a forest as it recovers from a fire. During the first 4 years after the fire, she records 2, 6, 18, and 54 trees. If this trend continues, which

expression can be used to find the number of trees after n years?

The expression is

Step-by-step explanation:

Geometric sequence:

In a geometric sequence, the quotient between consecutive terms is always the same.

The general rule of an geometric sequence is given by:

In which T(0) is the initial amount and q is the quotient.

During the first 4 years after the fire, she records 2, 6, 18, and 54 trees.

First term is 2, so .

Quotient is

So

The expression is

77

step-by-step explanation:

n=9

step-by-step explanation:

7 times a number = 7n

decreased by 13 = 7n-13

same as is =

5 times the number = 5n

increased by 5 = 5n+5

7n-13 = 5n+5

2n=18

n=9