Initial value problem using partial fractions

In summary, the conversation discusses an attempt at solving the equation (t+1) dx/dt = x^2 + 1 (t > -1), x(0) = pi/4 by placing like terms on either side and integrating. It is determined that there is no need for partial fractions and the solution is x = tan (ln |t + 1|) + pi/4.
  • #1
gkchristopher
1
0
(t+1) dx/dt = x^2 + 1 (t > -1), x(0) = pi/4

I have attempted to work this by placing like terms on either side and then integrating.

1/(x^2 + 1) dx = 1/(t + 1) dt

arctan x = ln |t + 1| + C

x = tan (ln |t + 1|) + C

pi/4 = tan(ln |0 + 1|) + C

pi/4 = C

x = tan (ln |t + 1|) + pi/4

Is this even close??
This was supposed to be a partial fractions exercise but I'm not seeing how. Thanks for any help.
 
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  • #2
No, I don't see any need for partial fractions. For the record, you can integrate 1/(x^2+1) by factoring x^2+1=(x+i)(x-i) and get an expression involving complex logs that is equivalent to arctan. But I don't know why you would want to.
 

1. What is an initial value problem?

An initial value problem is a type of differential equation where a function and its derivative are given at a specific point, and the goal is to find the function that satisfies the equation at all points.

2. How do you solve an initial value problem?

There are various methods for solving initial value problems, such as separation of variables, integrating factors, and using partial fractions. Each method involves manipulating the equation in different ways to isolate the function and its derivative.

3. What are partial fractions?

Partial fractions are a method used to simplify and solve complex rational expressions. They involve breaking down a rational expression into simpler fractions with distinct denominators, making it easier to solve.

4. When is it necessary to use partial fractions in solving an initial value problem?

Partial fractions are often necessary when the initial value problem involves a rational function. This is because the solution to the equation will also be a rational function, and using partial fractions can simplify the problem and make it easier to solve.

5. Can partial fractions be used to solve any type of initial value problem?

No, partial fractions can only be used in initial value problems that involve rational functions. In other cases, different methods such as separation of variables or integrating factors may be necessary to solve the problem.

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