The answer you have is good. You don't need to change anything.
Answer:
Function for given situation is : 
Value of computer after 4 years = $720.3.
Step-by-step explanation:
Given that the value of a $3000 computer decreases about 30% each year. Now we need to write a function for the computers value V(t). then we need to find about how much will the computer be worth in 4 years.
It clearly says that value decreases so that means function represents decay.
For decay we use formula:

where P=initial value = $3000,
r= rate of decrease =30% = 0.30
t= number of years
A=V(t) = future value
so the required function is 
or 
Now plug t=4 years to get the value of computer after 4 years.


Hence final answer is $720.3.
Answer:
(2,4)
Step-by-step explanation:
We have the system:
y=x+2
y=3x-2.
This is already setup for substitution.
I'm going to replace my first y with what the second y equals.
That is, I'm going to write 3x-2=x+2.
Time to solve the following for x:
3x-2=x+2
Subtract x on both sides:
2x-2= 2
Add 2 on both sides:
2x. = 4
Divide both sides by 2:
x. = 2
Now that we know x=2 and we have an equation that relates x to y: either y=x+2 or y=3x-2, doesn't matter which we use, we can find y.
So we y=x+2 with x=2 which means y=2+2=4.
So the solution, the intersection, is (2,4).
Answer:
The correct option is, Exponential Decay, $23,914.85.
Step-by-step explanation:
A farmer buys a tractor for $50,000.
It is provided that the the tractor depreciates 10% per year.
The exponential function for decay is:

Here,
a = initial value
r = decay rate
t = time
Compute the value of the tractor in 7 years as follows:


Thus, the correct option is, Exponential Decay, $23,914.85.