SOLUTION: the key in the back says the answer is 48, but i do not understand how they got there... f(n)= 5n(squared)+4n f(3)-9

Algebra ->  Functions -> SOLUTION: the key in the back says the answer is 48, but i do not understand how they got there... f(n)= 5n(squared)+4n f(3)-9      Log On


   

Question 145639This question is from textbook
: the key in the back says the answer is 48, but i do not understand how they got there... f(n)= 5n(squared)+4n f(3)-9 This question is from textbook

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
f(n)= 5n(squared)+4n; f(3)-9
:
Substitute 3 for n and subtract 9 from the result
f(3) = 5(3^2) + 4(3)
f(3) = 5(9) + 12
f(3) = 45 + 12 - 9 = 48