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The system of equations

\mathrm{-kx+3y-14z=25}\\

\mathrm{-15x+4y-kz=3}\\

\mathrm{-4x+y+3z=4}\\

is consistent for all \mathrm{k} in the set   

Option: 1

\mathrm{\mathbb{R}}


Option: 2

\mathrm{\mathbb{R}-\left \{ -11,13 \right \}}


Option: 3

\mathrm{\mathbb{R}-\left \{ 13 \right \}}


Option: 4

\mathrm{\mathbb{R}-\left \{ -11,11 \right \}}


Answers (1)

best_answer

For cosistance solutions \mathrm{\Delta \neq0}

\mathrm{\Rightarrow\left|\begin{array}{ccc} -k & 3 & -14 \\ -15 & 4 & -k \\ -4 & 1 & 3 \end{array}\right| \neq 0}

\mathrm{\Rightarrow-k(12+k)-3(-45-4 k)-14(-15+16) \neq 0}\\

\mathrm{\Rightarrow-12 k-k^{2}+135+12 k-14 \neq 0 }\\

\mathrm{\Rightarrow k^{2} \neq 121}\\

\mathrm{k \neq 11,-11}

Hence the correct answer is option 4

Posted by

Kuldeep Maurya

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