Chapter 11: Problem 28
Find the values of \(k\) for which \(y=x^{2}+k\) is a solution to the differential equation. $$ 2 y-x y^{\prime}=10 $$
Short Answer
Expert verified
The value of \(k\) is 5.
Step by step solution
01
Analyze the Given Solution
We are given the function \(y = x^2 + k\). To find the derivative \(y'\), differentiate with respect to \(x\).
02
Differentiate the Function
The derivative of \(y = x^2 + k\) with respect to \(x\) is \(y' = 2x\). This is because the derivative of \(x^2\) is \(2x\) and the derivative of a constant \(k\) is zero.
03
Substitute into the Differential Equation
Substitute \(y = x^2 + k\) and \(y' = 2x\) into the differential equation \(2y - xy' = 10\). This gives us:\[ 2(x^2 + k) - x(2x) = 10 \]
04
Simplify the Equation
Simplify the equation from Step 3:\[ 2x^2 + 2k - 2x^2 = 10 \]The \(2x^2\) terms cancel each other, simplifying to:\[ 2k = 10 \]
05
Solve for \(k\)
Solve the equation \(2k = 10\) by dividing both sides by 2:\[ k = \frac{10}{2} = 5 \]
06
Conclude the Solution
The solution to the differential equation using \(y = x^2 + k\) gives \(k = 5\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Derivative
The concept of a derivative is central to understanding calculus and the study of differential equations. In simple terms, a derivative represents the rate at which a function is changing at any given point. It's like the speed of a car at a particular moment, rather than its average speed over some distance. When we look at a function such as \( y = x^2 + k \), the derivative \( y' \) provides us with key information about the slope of the tangent line to the function at any point \( x \).
- To get the derivative of \( y = x^2 + k \), we differentiate each term in the equation.
- The derivative of \( x^2 \) is \( 2x \), because according to the power rule in calculus, \( x^n \)'s derivative is \( nx^{n-1} \).
- The constant \( k \) vanishes upon differentiation because its rate of change with respect to \( x \) is zero.
Differentiation
Differentiation is the process of finding a derivative, and it's a fundamental operation in calculus. It is used to determine how a function changes, making it invaluable in fields ranging from physics to economics. Let's explore differentiation in the context of our function \( y = x^2 + k \).
- To differentiate a function like \( y = x^2 + k \), employ rules such as the power rule and the constant rule.
- The power rule tells us how to handle terms like \( x^2 \), producing the derivative \( 2x \).
- The constant rule reminds us that the derivative of any constant is zero, as constants do not change with \( x \).
Mathematics Problem Solving
An essential skill in mathematics is being able to solve problems, and differential equations are excellent exercises for this. To solve a differential equation, follow a logical sequence of steps.First, you identify the given equation and its components. Here, the exercise provides the differential equation \( 2y - xy' = 10 \), and our candidate solution is \( y = x^2 + k \). Differentiation of \( y \) gives \( y' = 2x \).
- Substitute \( y \) and \( y' \) into the differential equation to check for compatibility.
- In this example, after simplification, the equation becomes \( 2k = 10 \), due to the cancellation of \( 2x^2 \) terms on either side.
- Finally, solve for the variable \( k \) to find that \( k = 5 \).