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Question: Answered & Verified by Expert
If $A=\left[\begin{array}{ccc}1 & -5 & 7 \\ 0 & 7 & 9 \\ 11 & 8 & 9\end{array}\right]$, then trace of matrix A is
MathematicsMatricesVITEEEVITEEE 2012
Options:
  • A 17
  • B 25
  • C 3
  • D 12
Solution:
1328 Upvotes Verified Answer
The correct answer is: 17
We knowthat, $\operatorname{tr}(A)=\sum_{i=1}^{n} a_{i i}$
$\therefore$ If $\mathrm{A}=\left[\begin{array}{ccc}1 & -5 & 7 \\ 0 & 7 & 9 \\ 11 & 8 & 9\end{array}\right]$, then $\operatorname{tr}(\mathrm{A})=1+7+9=17$

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