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The System of Equations: X + Y + Z = 5 X + 2y + 3z = 9 X + 3y + λZ = µ Has a Unique Solution, If (A) λ = 5, µ = 13 (B) λ ≠ 5 (C) λ = 5, µ ≠ 13 (D) µ ≠ 13 - Mathematics

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Question

The system of equations:
x + y + z = 5
x + 2y + 3z = 9
x + 3y + λz = µ
has a unique solution, if
(a) λ = 5, µ = 13
(b) λ ≠ 5
(c) λ = 5, µ ≠ 13
(d) µ ≠ 13

Options

  • λ = 5, µ = 13

  • λ ≠ 5

  • λ = 5, µ ≠ 13

  • µ ≠ 13

MCQ
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Solution

\[(b) \lambda \neq 5\]
\[\text{ For a unique solution,}\left| A \right|\neq 0.\]
\[ \Rightarrow \begin{vmatrix}1 & 1 & 1 \\ 1 & 2 & 3 \\ 1 & 3 & \lambda\end{vmatrix} \neq 0\]
\[ \Rightarrow 1\left( 2\lambda - 9 \right) - 1\left( \lambda - 3 \right) + 1\left( 3 - 2 \right) \neq 0\]
\[ \Rightarrow 2\lambda - 9 - \lambda + 3 + 1 \neq 0\]
\[ \Rightarrow \lambda - 5 \neq 0\]
\[ \Rightarrow \lambda \neq 5\]

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Chapter 8: Solution of Simultaneous Linear Equations - Exercise 8.4 [Page 23]

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RD Sharma Mathematics [English] Class 12
Chapter 8 Solution of Simultaneous Linear Equations
Exercise 8.4 | Q 10 | Page 23

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