Question

last year my math book cost $126,and i was told the price would increase 9% each year. If the cost continues to increase at this rate,what will my math book cost two years from now when i graduate? show your work.

Answer 1

it's a geometric sequence.
an=a1*r^(n-1)
a1=126
r=109%

an=126*(109%)^(n-1)

substitute n with 3 ( because in year 0 n will be 1, in year 1 n will be 2, and so on)

a3=126*(109%)^(3-1)
a3=149.7$

Answer 2

2,268 because u have to add the 2 years with 126