Solving differential equations

In summary, the given differential equation f"(x)=sinx is solved by integrating to find f'(x)=-cos(x)+C1 and then using the initial conditions x(0)=0 and x'(0)=1 to solve for the constant C1=2. The final solution is f(x)=-sin(x)+2x.
  • #1
chapsticks
38
0

Homework Statement




Solve the following differential equation:

f"(x)=sinx

x(0)=0, x'(0)=1

Homework Equations



x(0)=0, x'(0)=1

The Attempt at a Solution




f"(x)=sin(x)
integrate,
f'(x)=-cos(x)+C1
f'(0)=-cos(0)+C1=1 => C1=2
C1=2
f'(x)=-cos(x)+2
f(x)=-sin(x)+2x+C2
f(0)=-sin(0)+C2=0 => C2=0

=>
f(x)=-sin(x)+2x
 
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  • #2
It is correct.

ehild
 
  • #3
chapsticks said:

Homework Statement




Solve the following differential equation:

f"(x)=sinx

x(0)=0, x'(0)=1
Minor point, but this should be f(0) = 0, f'(0) = 1.
chapsticks said:

Homework Equations



x(0)=0, x'(0)=1

The Attempt at a Solution




f"(x)=sin(x)
integrate,
f'(x)=-cos(x)+C1
f'(0)=-cos(0)+C1=1 => C1=2
C1=2
f'(x)=-cos(x)+2
f(x)=-sin(x)+2x+C2
f(0)=-sin(0)+C2=0 => C2=0

=>
f(x)=-sin(x)+2x
What's your question?
 

FAQ: Solving differential equations

What is a differential equation?

A differential equation is a mathematical equation that relates a function to its derivatives. It describes how a quantity changes over time and can be used to model a wide range of phenomena in physics, engineering, and other scientific fields.

Why do we need to solve differential equations?

Differential equations are important because they allow us to mathematically model and understand complex systems and processes. They are used in many areas of science and engineering, such as predicting the motion of planets, designing electrical circuits, and studying population dynamics.

What methods are used to solve differential equations?

There are several methods for solving differential equations, including separation of variables, integrating factors, and numerical methods. The specific method used depends on the type of differential equation and the variables involved.

What is the difference between ordinary and partial differential equations?

Ordinary differential equations involve a single independent variable, such as time, and one or more dependent variables. Partial differential equations involve multiple independent variables and partial derivatives of the dependent variables. They are typically used to model systems in which multiple factors affect the change of a quantity.

What are some real-world applications of solving differential equations?

Differential equations are applied in many scientific and engineering fields, including physics, biology, chemistry, and economics. Some specific applications include predicting weather patterns, designing control systems for vehicles, and modeling chemical reactions in a lab setting.

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