Answer: The required value of f(3) is 81.
Step-by-step explanation: We are given the following function :

We are to find the value of f(3).
Substituting x = 3 in equation (i), we get

Thus, the required value of f(3) is 81.
They increased it by $10.
It ended up costing $60.
Hope this helps.
Answer:
f(x)=5x^3-2x^2-90x-36=0
=x^2(5x-2)-18(5x-2)=(x^2-18)(5x-2)=0
x^2-18=0/5x-2=0
x^2=18=x=9√2
5x-2=0
x=2/5
zeros are 9√2,2/5