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If the Points (X, −2), (5, 2), (8, 8) Are Collinear, Find X Using Determinants. - Mathematics

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प्रश्न

If the points (x, −2), (5, 2), (8, 8) are collinear, find x using determinants.

उत्तर

If the points (x, −2), (5, 2), (8, 8) are collinear, then
\[\begin{vmatrix}x & - 2 & 1 \\ 5 & 2 & 1 \\ 8 & 8 & 1\end{vmatrix} = 0\] 
\[ ∆ = \begin{vmatrix}x & - 2 & 1 \\ 5 & 2 & 1 \\ 8 & 8 & 1\end{vmatrix}\] 
\[ ∆ = \begin{vmatrix}x & - 2 & 1 \\ 5 - x & 4 & 0 \\ 8 & 8 & 1\end{vmatrix} \left[\text{ Applying }R_2 \to R_2 - R_1 \right]\]
\[ = \begin{vmatrix}x & - 2 & 1 \\ 5 - x & 4 & 0 \\ 8 - x & 10 & 0\end{vmatrix} \left[\text{ Applying }R_3 \to R_3 - R_1 \right]\]
\[ = \begin{vmatrix}5 - x & 4 \\ 8 - x & 10\end{vmatrix}\] 
\[ = 50 - 10x - 32 + 4x\] 
\[ = 18 - 6x\] 
\[ ∆ = 18 - 6x\] 
\[ ∆ = 0 \left[\text{ Given }\right]\] 
\[ \Rightarrow 18 - 6x = 0\] 
\[ \Rightarrow x = 3\]

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अध्याय 6: Determinants - Exercise 6.3 [पृष्ठ ७१]

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आरडी शर्मा Mathematics [English] Class 12
अध्याय 6 Determinants
Exercise 6.3 | Q 10 | पृष्ठ ७१

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