Math Problem Statement

2y''+5y'+-3y=0

Solution

You provided a second-order linear differential equation:

2y+5y3y=02y'' + 5y' - 3y = 0

This is a homogeneous linear differential equation with constant coefficients. The general approach is to solve it by finding the characteristic equation.

Step 1: Write the characteristic equation

To solve the differential equation, we first assume a solution of the form:

y=erty = e^{rt}

Substituting y=erty = e^{rt}, y=rerty' = re^{rt}, and y=r2erty'' = r^2 e^{rt} into the differential equation:

2r2ert+5rert3ert=02r^2 e^{rt} + 5r e^{rt} - 3e^{rt} = 0

Since erte^{rt} is never zero, we can divide through by erte^{rt}, which gives the characteristic equation:

2r2+5r3=02r^2 + 5r - 3 = 0

Step 2: Solve the characteristic equation

Now, we solve the quadratic equation:

2r2+5r3=02r^2 + 5r - 3 = 0

Using the quadratic formula r=b±b24ac2ar = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=2a = 2, b=5b = 5, and c=3c = -3, we get:

r=5±524(2)(3)2(2)r = \frac{-5 \pm \sqrt{5^2 - 4(2)(-3)}}{2(2)} r=5±25+244r = \frac{-5 \pm \sqrt{25 + 24}}{4} r=5±494r = \frac{-5 \pm \sqrt{49}}{4} r=5±74r = \frac{-5 \pm 7}{4}

Thus, we have two distinct real roots:

r1=5+74=24=12r_1 = \frac{-5 + 7}{4} = \frac{2}{4} = \frac{1}{2} r2=574=124=3r_2 = \frac{-5 - 7}{4} = \frac{-12}{4} = -3

Step 3: Write the general solution

Since the characteristic equation has two distinct real roots r1=12r_1 = \frac{1}{2} and r2=3r_2 = -3, the general solution to the differential equation is:

y(t)=c1er1t+c2er2ty(t) = c_1 e^{r_1 t} + c_2 e^{r_2 t} y(t)=c1e12t+c2e3ty(t) = c_1 e^{\frac{1}{2} t} + c_2 e^{-3t}

This is the general solution to the given differential equation.


Would you like more details on any specific part of the solution or have any other questions?

Related questions:

  1. How do we handle differential equations with repeated roots?
  2. What is the method to solve non-homogeneous differential equations?
  3. Can we solve higher-order linear differential equations in a similar manner?
  4. How does the Laplace transform method apply to solving differential equations?
  5. What are the initial conditions required to solve a differential equation uniquely?

Tip:

To determine specific values for the constants c1c_1 and c2c_2, you need initial or boundary conditions for the problem.

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Math Problem Analysis

Mathematical Concepts

Differential Equations
Characteristic Equations
Homogeneous Equations

Formulas

Characteristic equation: ar^2 + br + c = 0
Quadratic formula: r = (-b ± √(b^2 - 4ac)) / 2a

Theorems

Theory of Linear Homogeneous Differential Equations with Constant Coefficients

Suitable Grade Level

Undergraduate (Math or Engineering)