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Question #40702

Difficulty: 8/10 | 🟢 Free

The Question

Let Sk(n)=∑i=1nikS_k(n) = \sum_{i=1}^n i^k for k∈{1,2,3}k \in \{1, 2, 3\}. It is known that S1(n)=a1n2+b1n+c1S_1(n) = a_1 n^2 + b_1 n + c_1, S2(n)=a2n3+b2n2+c2nS_2(n) = a_2 n^3 + b_2 n^2 + c_2 n, and S3(n)=a3n4+b3n3+c3n2S_3(n) = a_3 n^4 + b_3 n^3 + c_3 n^2. Let MM be the 3×33 \times 3 matrix defined by M=[a1b1c1a2b2c2a3b3c3]M = \begin{bmatrix} a_1 & b_1 & c_1 \\ a_2 & b_2 & c_2 \\ a_3 & b_3 & c_3 \end{bmatrix}. Consider the system of linear equations M[xyz]=[αβγ]M \begin{bmatrix} x \\ y \\ z \end{bmatrix} = \begin{bmatrix} \alpha \\ \beta \\ \gamma \end{bmatrix}. If this system has infinitely many solutions, which of the following relations must hold true?

Options

  • A.

    α−3β+2γ=0\alpha - 3\beta + 2\gamma = 0

  • B.

    2α−3β+γ=02\alpha - 3\beta + \gamma = 0

  • C.

    α+2β−3γ=0\alpha + 2\beta - 3\gamma = 0

  • D.

    3α−2β−γ=03\alpha - 2\beta - \gamma = 0

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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

Sum of Powers of Natural Numbers|System of Linear Equations (Cramer/Inverse)|Elementary Row Operations

Why This Question Is Tricky

Common Mistakes

This question tests the synthesis of sequences and series (Faulhaber's formulas for the sum of powers) with linear algebra.

The trap lies in the assumption that a matrix formed by distinct polynomial coefficients is non-singular.

Students often rush to calculate the determinant using tedious fractions, risking arithmetic errors.

The elegant approach recognizes the rank deficiency through elementary row operations, revealing that the rows are linearly dependent.

This highlights the importance of structural analysis over brute-force computation in JEE Advanced.

Quick Facts About This Question

Question Information

SubjectMathematics
ChapterSequences and Series - Class 11
ConceptSum of Powers of Natural Numbers
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree