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X + Y + Z + W = 2 X − 2y + 2z + 2w = − 6 2x + Y − 2z + 2w = − 5 3x − Y + 3z − 3w = − 3 - Mathematics

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प्रश्न

x + y + z + w = 2
x − 2y + 2z + 2w = − 6
2x + y − 2z + 2w = − 5
3x − y + 3z − 3w = − 3

उत्तर

\[D = \begin{vmatrix}1 & 1 & 1 & 1 \\ 1 & - 2 & 2 & 2 \\ 2 & 1 & - 2 & 2 \\ 3 & - 1 & 3 & - 3\end{vmatrix}\] 

\[1\begin{vmatrix}- 2 & 2 & 2 \\ 1 & - 2 & 2 \\ - 1 & 3 & - 3\end{vmatrix} - 1\begin{vmatrix}1 & 2 & 2 \\ 2 & - 2 & 2 \\ 3 & 3 & - 3\end{vmatrix} + 1\begin{vmatrix}1 & - 2 & 2 \\ 2 & 1 & 2 \\ 3 & - 1 & - 3\end{vmatrix} - 1\begin{vmatrix}1 & - 2 & 2 \\ 2 & 1 & - 2 \\ 3 & - 1 & 3\end{vmatrix}\] 
\[ = 1\left[ - 2\left( 6 - 6 \right) - 2\left( - 3 + 2 \right) + 2\left( 3 - 2 \right) \right] - 1\left[ 1\left( 6 - 6 \right) - 2\left( - 6 - 6 \right) + 2\left( 6 + 6 \right) \right] + 1\left[ 1\left( - 3 + 2 \right) + 2\left( - 6 - 6 \right) + 2\left( - 2 - 3 \right) \right] - 1\left[ 1\left( 3 - 2 \right) + 2\left( 6 + 6 \right) + 2\left( - 2 - 3 \right) \right]\] 
\[ = 4 - 48 - 35 - 15\] 
\[ = - 94\]
\[ D_1 = \begin{vmatrix}2 & 1 & 1 & 1 \\ - 6 & - 2 & 2 & 2 \\ - 5 & 1 & - 2 & 2 \\ - 3 & - 1 & 3 & - 3\end{vmatrix}\] 
\[2\begin{vmatrix}- 2 & 2 & 2 \\ 1 & - 2 & 2 \\ - 1 & 3 & - 3\end{vmatrix} - 1\begin{vmatrix}- 6 & 2 & 2 \\ - 5 & - 2 & 2 \\ - 3 & 3 & - 3\end{vmatrix} + 1\begin{vmatrix}- 6 & - 2 & 2 \\ - 5 & 1 & 2 \\ - 3 & - 1 & - 3\end{vmatrix} - 1\begin{vmatrix}- 6 & - 2 & 2 \\ - 5 & 1 & - 2 \\ - 3 & - 1 & 3\end{vmatrix}\] 

\[ = 2\left[ - 2\left( 6 - 6 \right) - 2\left( - 3 + 2 \right) + 2\left( 3 - 2 \right) \right] - 1\left[ - 6\left( 6 - 6 \right) - 2\left( 15 + 6 \right) + 2\left( - 15 - 6 \right) \right] + 1\left[ - 6\left( - 3 + 2 \right) + 2\left( 15 + 6 \right) + 2\left( 5 + 3 \right) \right] - 1\left[ - 6\left( 3 - 2 \right) + 2\left( - 15 - 6 \right) + 2\left( 5 + 3 \right) \right]\] 
\[ = 188\] 
\[ D_2 = \begin{vmatrix}1 & 2 & 1 & 1 \\ 1 & - 6 & 2 & 2 \\ 2 & - 5 & - 2 & 2 \\ 3 & - 3 & 3 & - 3\end{vmatrix}\] 
\[1\begin{vmatrix}- 6 & 2 & 2 \\ - 5 & - 2 & 2 \\ - 3 & 3 & - 3\end{vmatrix} - 2\begin{vmatrix}1 & 2 & 2 \\ 2 & - 2 & 2 \\ 3 & 3 & - 3\end{vmatrix} + 1\begin{vmatrix}1 & - 6 & 2 \\ 2 & - 5 & 2 \\ 3 & - 3 & - 3\end{vmatrix} - 1\begin{vmatrix}1 & - 6 & 2 \\ 2 & - 5 & - 2 \\ 3 & - 3 & 3\end{vmatrix}\] 
\[1\left[ - 6\left( 6 - 6 \right) - 2\left( 15 + 6 \right) + 2\left( - 15 - 6 \right) \right] - 2\left[ 1\left( 6 - 6 \right) - 2\left( - 6 - 6 \right) + 2\left( 6 + 6 \right) \right] + 1\left[ 1\left( 15 + 6 \right) + 6\left( - 6 - 6 \right) + 2\left( - 6 + 15 \right) \right] - 1\left[ 1\left( - 15 - 6 \right) - 6\left( 6 + 6 \right) + 2\left( - 6 + 15 \right) \right]\] 
\[ = 1\] 
\[ D_3 = \begin{vmatrix}1 & 1 & 2 & 1 \\ 1 & - 2 & - 6 & 2 \\ 2 & 1 & - 5 & 2 \\ 3 & - 1 & - 3 & - 3\end{vmatrix}\] 
\[1\begin{vmatrix}- 2 & - 6 & 2 \\ 1 & - 5 & 2 \\ - 1 & - 3 & - 3\end{vmatrix} - 1\begin{vmatrix}1 & - 6 & 2 \\ 2 & - 5 & 2 \\ 3 & - 3 & - 3\end{vmatrix} + 2\begin{vmatrix}1 & - 2 & 2 \\ 2 & 1 & 2 \\ 3 & - 1 & - 3\end{vmatrix} - 1\begin{vmatrix}1 & - 2 & - 6 \\ 2 & 1 & - 5 \\ 3 & - 1 & - 3\end{vmatrix}\] 
\[ = 1\left[ - 2\left( 15 + 6 \right) + 6\left( - 3 + 2 \right) + 2\left( - 3 - 5 \right) \right] - 1\left[ 1\left( 15 + 6 \right) + 6\left( - 6 - 6 \right) + 2\left( - 6 + 15 \right) \right] + 2\left[ 1\left( - 3 + 2 \right) + 2\left( - 6 - 6 \right) + 2\left( - 2 - 3 \right) \right] - 1\left[ 1\left( - 3 - 5 \right) + 2\left( - 6 + 15 \right) - 6\left( - 2 - 3 \right) \right]\] 
\[ = - 141\] 
\[ D_4 = \begin{vmatrix}1 & 1 & 1 & 2 \\ 1 & - 2 & 2 & - 6 \\ 2 & 1 & - 2 & - 5 \\ 3 & - 1 & 3 & - 3\end{vmatrix}\] 
\[1\begin{vmatrix}- 2 & 2 & - 6 \\ 1 & - 2 & - 5 \\ - 1 & 3 & - 3\end{vmatrix} - 1\begin{vmatrix}1 & 2 & - 6 \\ 2 & - 2 & - 5 \\ 3 & 3 & - 3\end{vmatrix} + 1\begin{vmatrix}1 & - 2 & - 6 \\ 2 & 1 & - 5 \\ 3 & - 1 & - 3\end{vmatrix} - 2\begin{vmatrix}1 & - 2 & 2 \\ 2 & 1 & - 2 \\ 3 & - 1 & - 3\end{vmatrix}\] 
\[1\left[ - 2\left( 6 + 15 \right) - 2\left( - 3 - 5 \right) - 6\left( 3 - 2 \right) \right] - 1\left[ 1\left( 6 + 15 \right) - 2\left( - 6 + 15 \right) - 6\left( 6 + 6 \right) \right] + 1\left[ 1\left( - 3 - 5 \right) + 2\left( - 6 + 15 \right) - 6\left( - 2 - 3 \right) \right] - 2\left[ 1\left( - 3 - 2 \right) + 2\left( - 6 + 6 \right) + 2\left( - 2 - 3 \right) \right]\] 
\[ = 47\] 
Thus, 
\[x = \frac{D_1}{D} = \frac{188}{- 94} = - 2\] 
\[y = \frac{D_2}{D} = \frac{- 282}{- 94} = 3\] 
\[z = \frac{D_3}{D} = \frac{- 141}{- 94} = 1 . 5\] 
\[w = \frac{D_4}{D} = \frac{47}{- 94} = - 0 . 5\]

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अध्याय 6: Determinants - Exercise 6.4 [पृष्ठ ८४]

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आरडी शर्मा Mathematics [English] Class 12
अध्याय 6 Determinants
Exercise 6.4 | Q 20 | पृष्ठ ८४

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