Differentials with linear equations

You're missing a factor of y somewhere.In summary, the conversation involves finding the solution to the initial problem y'=y(1-x), y(1)=e and then solving for y(2). One attempt involves integrating both sides and solving for y, while another involves integrating the right hand side and using the fact that (yx)'=xy'+yx'. However, there are some errors in the calculations that need to be addressed.
  • #1
maiad
102
0

Homework Statement


Suppose that y(x) is the solution to the initial problem, y'=y(1-x), y(1)=e
find y(2)

Homework Equations


The Attempt at a Solution


This is my initial attempt:
[itex]\frac{dy}{dx}[/itex]=y(1-x)
[itex]\frac{dy}{y}[/itex]=(1-x)dx

i then integrated both side to get:
lny=-ln(1-x)+C

and here's the problem, if i plug in 1 to find c, ln(1-x) does not exist at that point...
 
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  • #2
I tried another approach:
y'+yx=y
(yx)'=y

integrated both sides:
yx=[itex]\frac{1}{2}[/itex]([itex]y^{2}[/itex]) +C

but with this approach i wasn't able to solve for y
 
  • #3
maiad said:
[itex]\frac{dy}{y}[/itex]=(1-x)dx

i then integrated both side to get:
lny=-ln(1-x)+C
First of all, you integrated the right hand side incorrectly. Remember, you're just integrating a polynomial.
 
  • #4
maiad said:
I tried another approach:
y'+yx=y
(yx)'=y
Wait a minute, (yx)'=xy'+yx'=xy'+y, not y'+yx.
 

FAQ: Differentials with linear equations

What is a differential equation?

A differential equation is a mathematical equation that relates a function with its derivatives. It is used to describe how a function changes over time or in relation to another variable.

What is a linear differential equation?

A linear differential equation is a differential equation in which the dependent variable and its derivatives appear only in a linear form. This means that the coefficients of the variables are constants and there are no higher powers or products of the variables present.

What is the purpose of solving differentials with linear equations?

The purpose of solving differentials with linear equations is to be able to predict and understand the behavior of a system over time. This can be applied to many real-world situations, such as population growth, economic trends, and physical processes.

What are the steps to solve a differential equation with a linear equation?

The general steps to solve a differential equation with a linear equation are: 1) Identify the dependent variable and its derivatives, 2) Determine the order of the differential equation, 3) Rewrite the equation in its standard form, 4) Solve for the integrating factor, 5) Integrate both sides of the equation, and 6) Apply any initial or boundary conditions to find the final solution.

What are some applications of differentials with linear equations?

Differentials with linear equations have many applications in various fields such as physics, engineering, economics, and biology. Some examples include predicting the growth of a population, modeling the flow of electricity in a circuit, and analyzing the spread of diseases.

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