Find the value of ' \(k\) ', if \(\left|\begin{array}{ccc} k-2 & 2 k-3 & 3 k-4 \\ k-4 & 2 k-9 & 3 k-16 \\…

Find the value of ' \(k\) ', if \(\left|\begin{array}{ccc} k-2 & 2 k-3 & 3 k-4 \\ k-4 & 2 k-9 & 3 k-16 \\ k-8 & 2 k-27 & 3 k-64 \end{array}\right|=0\)
  1. 1
  2. 2
  3. 3
  4. 4

Solution

It is given that, \(\left|\begin{array}{ccc} k-2 & 2 k-3 & 3 k-4 \\ k-4 & 2 k-9 & 3 k-16 \\ k-8 & 2 k-27 & 3 k-64 \end{array}\right|=0\) On applying, \(R_2 \longrightarrow R_2-R_1\) and \(R_3 \longrightarrow R_3-R_1\), we get \(\begin{aligned} & \Rightarrow \quad\left|\begin{array}{ccc} k-2 & 2 k-3 & 3 k-4 \\ -2 & -6 & -12 \\ -6 & -24 & -60 \end{array}\right|=0 \\ & \Rightarrow \quad\left|\begin{array}{ccc} k-2 & 2 k-3 & 3 k-4 \\ 1 & 3 & 6 \\ 1 & 4 & 10 \end{array}\right|=0 \\ & \Rightarrow \quad(k-2)[30-24]-(2 k-3)[10-6]+(3 k-4)[4-3]=0 \\ & \Rightarrow \quad 6 k-12-8 k+12+3 k-4=0 \Rightarrow k=4 \end{aligned}\)

Asked in: AP EAMCET 2020 (18 Sep Shift 1)

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