Solving 2nd Order ODEs: y^4 -3y'' -4y = 0

In summary, the conversation discusses a differential equation and the difficulty in solving it. The equation is y^4 -3y'' -4y = 0 and it can be rewritten as y'''' - 3y'' -4y = 0. The conversation mentions that the equation is hard to solve and may involve elliptic integral. The suggested solution is y=e^rx and the complementary solution is y=c_1*e^2x + c_2*e^-2x + c_3(sinx) + c_4(cosx).
  • #1
mj478
6
0
Hi. I am new to differential equations. This is probably pretty easy but I don't quite understand how to do it yet.

The equation is y^4 -3y'' -4y = 0.

I can figure out what class of equation it is. I can write it in the form y'' = F(y), but I am not really sure how to solve it.
 
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  • #2
Actually I think the problem is y'''' - 3y'' -4y. But I am still not sure what to do.
 
  • #3
mj478 said:
Actually I think the problem is y'''' - 3y'' -4y. But I am still not sure what to do.

Sure it is y'''' - 3y'' -4y = 0 because dasy to solve.
Solving y^4 - 3y'' -4y =0 is possible, but hard. It involves elliptic integral.
 
  • #4
This is ODE with constant coefficients..

Suppose that the solution is y=e^rx, than solve it!

i find that r=2, r=-2, r=i, r=-i

which means that

complementary solution of eqn is y=c_1*e^2x + c_2*e^-2x + c_3(sinx) + c_4(cosx)
 

Related to Solving 2nd Order ODEs: y^4 -3y'' -4y = 0

1. What is a 2nd order ODE?

A 2nd order ODE (ordinary differential equation) is an equation that relates a function and its derivatives up to the second order (e.g. y'', y''', etc.). It is commonly used in mathematical modeling to describe physical phenomena.

2. How do you solve a 2nd order ODE?

To solve a 2nd order ODE, you can use various methods such as separation of variables, substitution, or the characteristic equation. Each method involves manipulating the equation to isolate the dependent variable and its derivatives.

3. What does "y^4 -3y'' -4y = 0" mean?

This is the general form of a 2nd order ODE. The term "y^4" represents the highest order derivative (in this case, the fourth derivative) of the function y. The coefficients -3 and -4 represent the coefficients of the second and first derivatives, respectively.

4. Can this ODE be solved analytically?

Yes, this ODE can be solved analytically using various methods as mentioned in question 2. The solution will be a function of the independent variable (x) and will depend on the initial conditions of the problem.

5. What is the significance of solving a 2nd order ODE?

Solving a 2nd order ODE allows us to find a mathematical expression for the relationship between a function and its derivatives, which can then be used to make predictions or analyze the behavior of a system. This is particularly useful in the fields of physics, engineering, and economics.

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