-b.3.1.1 find the general solution of the second order y''+2y'-3y=0

In summary, The general solution of the second order differential equation $y''+2y'-3y=0$ is $y = c_1e^{-3t}+c_2e^{t}$, where $c_1$ and $c_2$ are constants. This is found by assuming that $y = e^{rt}$ and solving for the roots of $r$ in the characteristic equation $r^2+2r-3=0$. Two linearly independent solutions are $y = e^{-3t}$ and $y = e^{t}$, and the general solution is a linear combination of these solutions. Linearly independent solutions are defined as two differentiable functions that cannot be expressed as
  • #1
karush
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$\tiny{3.1.1}$
find the general solution of the second order differential equation.
$$y''+2y'-3y=0$$
assume that $y = e^{rt}$ then,
$$r^2+2r-3=0\implies (r+3)(r-1)=0$$
new stuff... so far..
 
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  • #2
karush said:
$\tiny{3.1.1}$
find the general solution of the second order differential equation.
$$y''+2y'-3y=0$$
assume that $y = e^{rt}$ then,
$$r^2+2r-3=0\implies (r+3)(r-1)=0$$
new stuff... so far..
Good so far. So r = -3 and r = 1. Therefore two linearly independent solutions would be \(\displaystyle y = e^{-3t}\) and \(\displaystyle y = e^{t}\).

One last little bit for you. We have two linearly independent solutions to a second order linear homogenous differential equation. How do you write down the general solution?

-Dan
 
  • #3
topsquark said:
Good so far. So r = -3 and r = 1. Therefore two linearly independent solutions would be \(\displaystyle y = e^{-3t}\) and \(\displaystyle y = e^{t}\).

One last little bit for you. We have two linearly independent solutions to a second order linear homogenous differential equation. How do you write down the general solution?

-Dan
$$y=c_1e^{-3t}+c_2e^{t}$$

guess that's it?

what is linear independent solutions?
 
  • #4
karush said:
$$y=c_1e^{-3t}+c_2e^{t}$$

guess that's it?

what is linear independent solutions?
Yes, that's it.

Let f(t) and g(t) be differentiable functions. Then they are called linearly dependent if there are nonzero constants c1 and c2 with \(\displaystyle c_1 f(t) + c_2 g(t) = 0\) for all t. If they are not linearly dependent then they are linearly independent.

-Dan
 

1. What is a second order differential equation?

A second order differential equation is a mathematical equation that involves a function and its second derivative. It is commonly used to model physical phenomena in science and engineering.

2. How do you find the general solution of a second order differential equation?

To find the general solution of a second order differential equation, you need to solve for the function that satisfies the equation. This can be done by using techniques such as separation of variables, variation of parameters, or the method of undetermined coefficients.

3. What is the difference between a general solution and a particular solution?

A general solution is a solution that satisfies the given differential equation for all possible values of the independent variable. On the other hand, a particular solution is a specific solution that satisfies the equation for a specific set of initial conditions.

4. How can the general solution of a second order differential equation be used in science?

The general solution of a second order differential equation can be used to model and predict the behavior of physical systems in science. It can also be used to analyze and understand the underlying mathematical principles of various phenomena.

5. Can the general solution of a second order differential equation be applied to real-world problems?

Yes, the general solution of a second order differential equation can be applied to real-world problems in science and engineering. It can be used to solve problems related to motion, electrical circuits, and other physical systems.

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