Chapter 4: Problem 87
Let a solution \(y=y(x)\) of the differential equation \(x \sqrt{x^{2}-1} d y-y \sqrt{y^{2}-1} d x=0\) satisfy \(y(2)=\frac{2}{\sqrt{3}}\) Statement I \(y(x)=\sec \left(\sec ^{-1} x-\frac{\pi}{6}\right)\) and Statement II \(y(x)\) is given by \(\frac{1}{y}=\frac{2 \sqrt{3}}{x}-\sqrt{1-\frac{1}{x^{2}}}\)
Short Answer
Step by step solution
Understand the differential equation
Substitution and transformation
Solve for y(x) using separate variables
Verify statement I
Derive statement II
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Initial Conditions
When solving differential equations, the general solution may include arbitrary constants. Initial conditions allow us to find the specific values for these constants, providing a unique solution tailored to meet these starting parameters. This is crucial because without initial conditions, there could be infinitely many solutions that fit the differential equation.
To apply the initial condition, substitute \(x = 2\) and \(y = \frac{2}{\sqrt{3}}\) into the derived general solution. This would then allow us to solve for any constants and verify that the solution meets the given conditions.
Substitution Method in Differential Equations
The differential \(dx\) then becomes \( \sec(u)\tan(u)du\) through differentiation. In the process of substitution, our goal is to express the equation in terms of new variables where familiar techniques, such as separation of variables, can be applied efficiently.
Substitution may also require altering \(y\) and dealing with its changes similarly, connecting to initial conditions to keep transformations consistent throughout the process.
Variable Separation Technique
For this problem, after substitution, the equation can be rewritten such that all terms involving \(x\) are on one side and all terms involving \(y\) are on the other. This separation allows us to integrate each side independently, with respect to its own variable.
Once the equation is separated, you obtain integrable forms. Integration of both sides yields a solution that includes integration constants, which can then be determined by using initial conditions. The success of this method depends on achieving a neatly separated equation where integration is straightforward.
Integration in Solving Differential Equations
For instance, integrating one side of the equation with respect to \(x\), and the other side concerning \(y\), provides a relationship between these two variables. This technique helps transition from a differential form to an algebraic expression, offering a wider understanding of the relationship between \(x\) and \(y\).
Once you integrate both sides, the result is often accompanied by an integration constant. This constant plays a pivotal role because, when you apply the initial conditions, you solve for it, leaving you with a specific solution that satisfies the initial conditions provided in the problem statement. Integration is thus not simply a procedure but a transformation from an equation of rates to one of cumulative values, essential for capturing the dynamics described by a differential equation.