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Question: Answered & Verified by Expert
If $2 x+3 y-5 z=7, x+y+z=6,3 x-4 y+2 z=1$, then $x=$
MathematicsDeterminantsJEE Main
Options:
  • A $\left|\begin{array}{ccc}2 & -5 & 7 \\ 1 & 1 & 6 \\ 3 & 2 & 1\end{array}\right| \div\left|\begin{array}{ccc}7 & 3 & -5 \\ 6 & 1 & 1 \\ 1 & -4 & 2\end{array}\right|$
  • B $\left|\begin{array}{ccc}-7 & 3 & -5 \\ -6 & 1 & 1 \\ -1 & -4 & 2\end{array}\right| \div\left|\begin{array}{ccc}2 & 3 & -5 \\ 1 & 1 & 1 \\ 3 & -4 & 2\end{array}\right|$
  • C $\left|\begin{array}{ccc}7 & 3 & -5 \\ 6 & 1 & 1 \\ 1 & -4 & 2\end{array}\right| \div\left|\begin{array}{ccc}2 & 3 & -5 \\ 1 & 1 & 1 \\ 3 & -4 & 2\end{array}\right|$
  • D None of these
Solution:
1395 Upvotes Verified Answer
The correct answer is: $\left|\begin{array}{ccc}7 & 3 & -5 \\ 6 & 1 & 1 \\ 1 & -4 & 2\end{array}\right| \div\left|\begin{array}{ccc}2 & 3 & -5 \\ 1 & 1 & 1 \\ 3 & -4 & 2\end{array}\right|$
For the given set of equation, by Cramer's Rule
$x=\frac{D_x}{D}=\left|\begin{array}{ccc}7 & 3 & -5 \\ 6 & 1 & 1 \\ 1 & -4 & 2\end{array}\right| \div \left|\begin{array}{ccc}2 & 3 & -5 \\ 1 & 1 & 1 \\ 3 & -4 & 2\end{array}\right|$.

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