Question:

The order and degree of the differential equation : \( \frac{d}{dx}(y')^3 + (y')^3 = 1 \) respectively are where \( y' = \frac{dy}{dx} \)

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Always perform indicated operations like \( \frac{d}{dx} \) before determining the order and degree.
Ensure all derivatives are free from radicals or fractional exponents to correctly identify the degree.
Updated On: Sep 10, 2026
  • \( 1, 3 \)
  • \( 2, 1 \)
  • \( 3, 1 \)
  • \( 3, 2 \)
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The Correct Option is B

Solution and Explanation

Concept:
Order: The order of a differential equation is the order of the highest derivative present in the equation.
Degree: The degree is the power of the highest order derivative, provided the equation is a polynomial in its derivatives.

Step 1:
Expand the given differential equation
The given equation is: \[ \frac{d}{dx}(y')^3 + (y')^3 = 1 \] We need to perform the differentiation in the first term with respect to \( x \). Using the chain rule: \[ \frac{d}{dx} \left( \frac{dy}{dx} \right)^3 = 3 \left( \frac{dy}{dx} \right)^2 \cdot \frac{d}{dx} \left( \frac{dy}{dx} \right) \] \[ = 3(y')^2 \cdot y'' \]

Step 2:
Rewrite the full equation
Substituting the derivative back into the original equation: \[ 3(y')^2 y'' + (y')^3 = 1 \] Or in standard notation: \[ 3 \left( \frac{dy}{dx} \right)^2 \left( \frac{d^2y}{dx^2} \right) + \left( \frac{dy}{dx} \right)^3 = 1 \]

Step 3:
Identify the order and degree
The highest derivative present in the equation is the second derivative, \( y'' \) or \( \frac{d^2y}{dx^2} \). Therefore, the order is 2. The highest order derivative term is \( 3(y')^2 y'' \). The exponent (power) of this term \( (y'') \) is 1. Therefore, the degree is 1.
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