Hi!
Samuel bought the mixer for $54,205. The value of this (the prive) decreases every year at a costant rate (so, for example, it may decrease of $100 every year).
we are solving for t and we should keep in mind that we multiply the price for the function (1 - rate/100)^time
in f(t) you put the value of year 1 for example

Solving for r will bring us to the solution, and we can substitute 1 to t since we are calculating how much it decreases after ONE year.
We would divide for 54205 to cancel out that 54205 multiplicating the parenthesis.
Also, the x is given by the formula (vale2-value1)/value1 to see how much the price changes from year 1 to year 2
We will get

Again, it would be:
f(t) = 54205(0.13)^1
The y- intercept of this equation is 4/1=4.00000
Explanation: y tells us how far up the line goes Notice that when x = 0 the value of y is 4/1 so this line "cuts" the y axis at y= 4.00000
For
(x-h)^2=4p(y-k)
vertex is (h,k)
distance from vertex to directix=p=distance from vertex to focus
|4p|=focal width
remember, focus is on the side of the parabola where it opens and directix is at the back
when p is negative, it opens down
when p is positive, it opens up
look at equation
-1/40(x-0)^2=(y-0)
times -40 to both sides
(x-0)^2=-40(y-0)
(x-0)^2=4(-10)(y-0)
vertex=(0,0)
p=-10,it's negative so it opens down
focus is 10 units below vertex (y direction)
focus=(0,-10)
diretix is 10 above
directix is y=10
focal width=|4p|=|4(-10)|=|-40|=40
vertex=(0,0)
focus=(0,-10)
directix is y=10
focal width=40 units
This problem calls for calculating the unit cost in each case and then comparing the unit costs.
$1.79
---------- = $0.09/oz
20 oz
Noting that 1 lb = 16 oz,
$2.59
---------- = $0.14
18 oz
$1.79 for 20 oz is definitely the better buy (less expensive) when compared to $2.59 for 18 oz.