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:
30
Step-by-step explanation:
7 1/2 is 15/2 as an improper fraction
15/2 ÷ 1/4 = 15/2 · 4 which is 30
Answer:
six is 3 pointers 4 is the 2 pointers
Step-by-step explanation:
Hello!
To find how much less Marvin pays per liter using his loyalty card, we can subtract the discounted value from the original value.
1.679 - 1.439 = 0.24
Therefore, Melvin pays 0.24 dollars less per liter using his loyalty card.