Answer:
75
Step-by-step explanation:
f(1) = 7
f(n) = 3f(n-1) + 3
So what you are trying to do here is find the recursive value (that's what it is called) for f(n). Computers love this sort of thing, but we humans have to do it slowly and carefully.
So let's try f(2)
That means that f(2) = 3*f(n-1) + 3
but if f(2) is used it means that you have to know f(2-1) which is just f(1) and we know that.
so f(2) = 3*f(1)+3
f(2) = 3*7 + 3
f(2) = 21 + 3
f(2) = 24
Now do it again. We now know F(2), so we should be able to find f(3)
f(3) = 3*f(3 - 1) + 3
f(3) = 3*f(2) + 3 We know that f(2) = 24
f(3) = 3* 24 + 3
f(3) = 72 + 3
f(3) = 75
It equal to .3333333333333333333333333333333333......
To find the total amount, you will use the formula for finding compounded interest. This means you will be paid interest on top of the interest you have earned each year.
A = P(1 + r)^nt
P stands for the principal.
r is the interest rate when compounded annually
nt is the number of years
A = 17.50(1 + 0.04)^25
A = $46.65
This person would have $46.65 after 25 years.
Let's call the 13¢ stamps a and the 18¢ stamps b:
a+b = 42 and therefore a= 42-b (formula 1)
0.13a+0.18b= 6.66 In this formula, substitute the value of a according to formula 1:
0.13(42-b)+0.18b= 6.66 Multiply on the left to get rid of the parenthesis:
5.46-0.13b+0.18b= 6.66 Subtract 5.46 from both sides:
-0.13b+0.18b= 1.20 Add on the left:
0.05b= 1.20 Divide both sides by 0.05
b= 24 You have 24 18¢ stamps and:
42-24= 18 13¢ stamps
Check: (24 x 0.18) + (18 x 0.13)= 6.66 Correct.
