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GATE 2010 CS (CS1) – Question 39

Engineering Mathematics · Linear Algebra · 2 marks · Multiple choice

The matrix $\begin{pmatrix}2&3\\x&y\end{pmatrix}$ has eigenvalues 4 and 8. Find x,y.

  1. x=4,y=10
  2. x=5,y=8
  3. x=−3,y=9
  4. x=−4,y=10

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Correct answer: (D) x=−4,y=10

Explanation

The trace equals the sum of eigenvalues: 2+y=12, giving y=10. The determinant equals their product: 2y−3x=32. Substituting gives 20−3x=32, hence x=−4. Thus D.

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