You're original equation has a -81, so the factored form will have to have a positive and negative multiplying one another to achieve that...
f(x) = x(x + 9)(x - 9)
Answer: 6.93 years
Step-by-step explanation:
Given
Rate of interest is 
Future value is given by 
For the investment to double itself, i.e. 

It takes around 6.93 years to double the investment.
Its 56$ and you saved 14$
Answer:
Area =
square centimeter
If the circumference of the hub cap would have been smaller, then its radius would have been smaller and subsequently its area would also have been less.
Step-by-step explanation:
As we know the circumference of a circle is 
The radius of the hub cap needs to be devised to determine the area


centimeters
Area of the hub cap = 
Substituting the devised value of r in the above equation, we get -

square centimeter
If the circumference of the hub cap would have been smaller, then its radius would have been smaller and subsequently its area would also have been less.