The constant variation of k is 40. Hope that helps.
Answer: 42804 people per square mile
Step-by-step explanation:
As we know Population density = 
Given, population of New York City = 8.55 million
Area of New York City = 300 square miles
Then, population density of New York City = 
[1 million = 1,000,000]
Population of Manhattan = 1.64 million = 1640000
Area of Manhattan = 23 square miles
population density of Manhattan = 
Difference = 71304 - 28500 =42804
Hence, population density of Manhattan is 42804 people per square mile greater than that of New York City.
Answer:

Step-by-step explanation:
Hello,
let's follow the advise and proceed with the substitution
first estimate y'(x) and y''(x) in function of y'(t), y''(t) and t

Now we can substitute in the equation
![x^2y''(x)+9xy'(x)-20y(x)=0\\ e^{2t}[ \ e^{-2t}(\dfrac{d^2y}{dt^2}-\dfrac{dy}{dt}) \ ] + 9e^t [ \ e^{-t}\dfrac{dy}{dt} \ ] -20y=0\\ \dfrac{d^2y}{dt^2}-\dfrac{dy}{dt}+ 9\dfrac{dy}{dt}-20y=0\\ \dfrac{d^2y}{dt^2}+ 8\dfrac{dy}{dt}-20y=0\\](https://tex.z-dn.net/?f=x%5E2y%27%27%28x%29%2B9xy%27%28x%29-20y%28x%29%3D0%5C%5C%3C%3D%3E%20e%5E%7B2t%7D%5B%20%5C%20e%5E%7B-2t%7D%28%5Cdfrac%7Bd%5E2y%7D%7Bdt%5E2%7D-%5Cdfrac%7Bdy%7D%7Bdt%7D%29%20%5C%20%5D%20%2B%209e%5Et%20%5B%20%5C%20e%5E%7B-t%7D%5Cdfrac%7Bdy%7D%7Bdt%7D%20%5C%20%5D%20-20y%3D0%5C%5C%3C%3D%3E%20%5Cdfrac%7Bd%5E2y%7D%7Bdt%5E2%7D-%5Cdfrac%7Bdy%7D%7Bdt%7D%2B%209%5Cdfrac%7Bdy%7D%7Bdt%7D-20y%3D0%5C%5C%3C%3D%3E%20%5Cdfrac%7Bd%5E2y%7D%7Bdt%5E2%7D%2B%208%5Cdfrac%7Bdy%7D%7Bdt%7D-20y%3D0%5C%5C)
so the new equation is

the auxiliary equation is

so the solutions of the new equation are

with a and b real
as


hope this helps
do not hesitate if you have any questions
Answer:
Step-by-step explanation:
A company manufactures two types of fishing rods, standard and folding. The cost of manufacturing 2 folding rods and 1 standard is $35. If 5 standard and 7 folding rods were manufactured, the cost would be $145. How much does it cost to manufacture each type of rod.
let S = standar rod
F= folding rod
2F + S =35
2F + S -2F =35 - 2F
or S = 35-2F
7F + 5S =145
7F + 5S -7F =145 -7F
or 5S =145-7F
Since S=35-2F
5S = 5X (35-2F)
5S = 175 -10F
which equals 145-7F
175-10F = 145-7F
175-10F +10F = 145 -7F + 10F
175 = 145 +3F
175 -145 =145 -145 + 3F
30 = 3F
F = 10
but S =35 - 2F
so S = 35 -2X10
S = 35-20 =15
check:
if F = 10 and S = 15
then 5S +7F should equal 145
5X15 + 7X10 = 75 + 10 =145
so F=10, S=15