Calculus HW Question 9 & 10 only

9.

 

In 2000 a phone company’s net income was 4300 million dollars and changing at the rate of 800x² – 4800x + 5200 million dollars per year, where x is the number of years since 2000 (for x ≤ 6). Find a formula I(x) for the phone company’s net income at any time x.

I(x) = ______________________

Use your formula to find their income in 2003.
I(3) = $ [removed]million

 

10.

 

A person can memorize words at the rate of 5/√t words per minute.

(a) Find a formula f(t) for the total number of words that can be memorized in t minutes. [Hint: Evaluate C so that 0 words have been memorized at time t = 0.]
f(t) = _______________________

(b) Use the formula that you found in part (a) to find the total number of words that can be memorized in 9 minutes.
[removed]words