Question

What is the order of the differential equation? $$ y^{\prime \prime}+3 t y^{3}=1 $$

Short answer

Answer: The order of the given differential equation is 2.

Step-by-step solution

Identifying the highest derivative

First, we need to identify the highest derivative in the given equation. In our differential equation, the derivatives are denoted by the prime notation: $$ y^{\prime \prime} + 3ty^{3} = 1 $$ Here, \(y^{\prime\prime}\) represents the second derivative of the function \(y\) with respect to the independent variable \(t\). This is the highest derivative in the equation as there are no other terms with a higher prime notation.

Determine the order of the differential equation

Now that we have identified the highest derivative in the equation, we can determine the order of the differential equation. The order of the differential equation is equal to the highest derivative present. In this case, the highest derivative is \(y^{\prime\prime}\) which is the second derivative. Therefore, the order of the given differential equation is 2.

Key concepts

Order of a Differential Equation

The order of a differential equation is an important concept in mathematics, especially when analyzing different types of physical systems. It dictates the degree of the highest derivative present in the equation. This means that if you're looking at a differential equation, to determine its order, you should:

• First, identify all the derivative terms.
• Then, find the derivative with the highest order (such as the first, second, third derivative, etc.).

For instance, in the given example from the original exercise \(y^{\prime \prime} + 3ty^{3} = 1\), the highest derivative present is \(y^{\prime\prime}\), which is the second derivative of \(y\). Therefore, this differential equation is of order 2. Higher-order equations, such as third or fourth order, mean deeper complexity but follow the same principle of identifying the highest order derivative.

Highest Derivative

Identifying the highest derivative in a differential equation is the key step in determining its order. The term "highest derivative" refers to the term containing the greatest number of derivative notations.
Here's how you can identify it:

• Look for the derivative symbols (such as primes or differentials) in the equation.
• The derivative term which appears with the most number of primes or highest differential signifies the highest derivative.

In the differential equation from the exercise \(y^{\prime \prime} + 3ty^{3} = 1\), \(y^{\prime\prime}\) is marked with two prime symbols. This indicates that it's the second derivative and also the highest derivative in this equation. Finding the highest derivative is crucial as it gives you a direct insight into the behavior and complexity of the differential equation being analyzed.

Prime Notation

Prime notation is a compact and convenient way to denote derivatives, commonly used in calculus and differential equations.
It provides an easy shorthand for indicating derivatives:

• A single prime \(y'\) represents the first derivative of \(y\).
• Two primes \(y''\) denote the second derivative.
• Three primes \(y'''\) indicate the third derivative, and so on.

In the given exercise \(y^{\prime \prime} + 3ty^{3} = 1\), the prime notation \(y^{\prime \prime}\) expresses that it's the second derivative. This form of notation is very helpful in simplifying the writing and solving of equations, especially when you deal with complex differential scenarios. Moreover, its widespread use in textbooks and scientific work makes it essential for students to grasp and use it effectively to interpret and solve problems involving derivatives correctly.