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Question #40677

Difficulty: 8/10 | 🟢 Free

The Question

Let a differential equation be given by α(d4ydx4)5+β(d3ydx3)7+γ(d2ydx2)4+(dydx)6=ex\alpha \left( \frac{d^4y}{dx^4} \right)^5 + \beta \left( \frac{d^3y}{dx^3} \right)^7 + \gamma \left( \frac{d^2y}{dx^2} \right)^4 + \left( \frac{dy}{dx} \right)^6 = e^x where the coefficients are defined as: α=∑n=1∞1n(n+1)(n+2)−14\alpha = \sum_{n=1}^{\infty} \frac{1}{n(n+1)(n+2)} - \frac{1}{4} β=∑n=1∞2n−13n−1\beta = \sum_{n=1}^{\infty} \frac{2^{n-1}}{3^n} - 1 γ=∑n=1∞1n(n+2)\gamma = \sum_{n=1}^{\infty} \frac{1}{n(n+2)} If OO and DD represent the order and degree of the differential equation respectively, find the value of O+DO + D.

Options

  • A.

    6

  • B.

    7

  • C.

    9

  • D.

    10

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Bridge

Practice problems that bridge the gap between foundational theory and advanced practical application.

Concepts Behind This Question

Infinite GP Convergence|V-N Method (Partial Fractions)|Order and Degree Definition

Why This Question Is Tricky

Common Mistakes

This question tests the fundamental definition of the order and degree of a differential equation by embedding infinite series (V-N method and Geometric Progression) as coefficients.

The primary trap is procedural reflex: students often assume the highest written derivative dictates the order without verifying if its coefficient evaluates to zero.

By forcing the evaluation of these limits, the problem distinguishes between students who blindly apply definitions and those who recognize that a vanishing coefficient eliminates the term entirely, thereby altering the differential equation's true order and degree.

Quick Facts About This Question

Question Information

SubjectMathematics
ChapterSequences and Series - Class 11
ConceptInfinite GP Convergence
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree