Finding a Second Solution to (x-1)y"-xy'+y=0

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In summary, using reduction of order, a second solution to the given differential equation can be found by substituting y(t)=v(t)e^x, y'(t)= v'(t)e^x +v(t)e^x, and y"(t)= v"(t)+2v'(t)e^x +v(t)e^x into the initial equation. Simplifying will result in the v-term disappearing, providing the second solution.
  • #1
Punchlinegirl
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Use reduction of order to find a second solution to the given differential equation
(x-1)y"-xy'+y=0 x>1 y_1=e^x


Putting it in standard form gives
[tex] y"-x/x-1 y' + 1/x-1 y =0 [/tex]
y(t)=v(t)e^x
y'(t)= v'(t)e^x +v(t)e^x
y"(t)= v"(t)+2v'(t)e^x +v(t)e^x
plugging into the initial equation:
[tex] v"(t)e^x+2v'(t)e^x+v(t)e^x-xv'(t)e^x/x-1 +xv(t)e^x/x-1 +v(t)e^x/x-1 [/tex]

I'm not sure how to simplify this further if it can even be done, or what I should do next. Can someone please help me out?
 
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  • #2
Leave it in the form: (x-1)y"-xy'+y=0 x>1 y_1=e^x

then substitute in the y, y' and y'' values for the 2nd solution.

Simplify and you will find the v-term disappear. I just did :)
 

1. What is the purpose of finding a second solution to (x-1)y'-xy'+y=0?

The purpose of finding a second solution is to determine whether the given differential equation has more than one solution. This can be helpful in certain applications, such as in physics or engineering, where multiple solutions may have different physical interpretations or provide additional insights into the problem.

2. How do you find a second solution to (x-1)y'-xy'+y=0?

To find a second solution, you can use the method of reduction of order. This involves assuming a second solution of the form y2(x) = u(x)y1(x), where y1(x) is the known first solution and u(x) is a function to be determined. Substituting this into the original differential equation and solving for u(x) will give you the second solution.

3. Can a second solution always be found for (x-1)y'-xy'+y=0?

No, a second solution may not always exist. For example, if the first solution is a constant function, then there is no u(x) that satisfies the reduction of order equation. In addition, if the first solution is a polynomial of degree n, then the second solution can only be found if the differential equation has a polynomial of degree n+1 as its solution.

4. How does finding a second solution to (x-1)y'-xy'+y=0 relate to the general solution?

Once you have found the second solution, you can use it to form the general solution of the differential equation. The general solution will have the form y(x) = c1y1(x) + c2y2(x), where c1 and c2 are constants and y1(x) and y2(x) are the first and second solutions, respectively.

5. Are there any other methods for finding a second solution to (x-1)y'-xy'+y=0?

Yes, there are other methods such as the method of variation of parameters and the method of power series. These methods can be used to find a second solution in cases where the method of reduction of order is not applicable. However, these methods may be more complex and time-consuming compared to the method of reduction of order.

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