Justin wants to paint his room. So he put together some
quotations from two different painters. The first painter's total charge was
based on the number of hours (denoted as x) worked was modeled as
f( x ) = 70 + 5 x, while that of the second painter was
g( x ) = 30 + 15 x. Justin knows that it will take more than 4
hours to decorate the house so he was certain to go with the first painter
whose cost is low-priced when the number of hours is above 4 hours.
We call x the 4 points-worth problems and y the 3 points-worth problems
You know that x+y = 32
4x+3y = 111
You know that the difference from the x and y is 32 so write:
x = 32-y
Substitute at x the value of 32-y
4(32-y)+3y = 111
128-4y +3y = 111
-4y+3y = 111-128
-y = -17
y = 17
We will see that the exponential decay function is:
f(x) = 175*(0.8)^x
<h3>
How to find the exponential decay?</h3>
The general exponential decay is:
f(x) = A*(1- r)^x
Where:
- A is the initial value.
- r is the rate of decay in decimal form.
- x is the variable, in this case is the time.
Here we know that the initial value is 175, and the rate of decay is 20%. To get this in decimal form, we just divide it by 100%.
20%/100% = 0.2
Replacing that in the exponential function, we get:
f(x) = 175*(1 - 0.2)^x
f(x) = 175*(0.8)^x
If you want to learn more about exponential functions, you can read:
brainly.com/question/11464095
Answer:
a)
b) 0.09
Step-by-step explanation:
We are given the following in the question:
where B(t) gives the brightness of the star at time t, where t is measured in days.
a) rate of change of the brightness after t days.
b) rate of increase after one day.
We put t = 1
The rate of increase after 1 day is 0.09
