5 2/5 is the answer as a mixed number
Answer:
k = 30, 
Step-by-step explanation:
Since
is a solution, then it must satisfy the differential equation. So, we calculate the derivatives and replace the value in the equation. We have that

Then, replacing the derivatives in the equation we have:

Since
is a positive function, we have that
.
Now, consider a general solution
, then, by calculating the derivatives and replacing them in the equation, we get

We already know that r=5 is a solution of the equation, then we can divide the polynomial by the factor (r-5) to the get the other solution. If we do so, we get that (r-6)=0. So the other solution is r=6.
Therefore, the general solution is

We are asked to express r in terms of A, P, and t.
We first divide both sides of the equation by t, which gives us

,
then, dividing both sides by P, we have

.
Swap the sides:
Finally subtracting 1 from both sides gives us

.
Answer:
40% decrease
Step-by-step explanation:
First, let's find the value decrease of the item from yesterday to today
$65 - $39 = $26
That means that $65 was 100% of the price and decreasing it by 26 gets us to 39
We need to find the percentage of 39 in 65
39/65 = 0.6 or 60%
If 39 is 60% of 65, then there was a 40% decrease form 100%
To check we can calculate the percentage of 26 in 65:
26/65 = 40%
There was a 40% decrease
-Chetan K