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
- 2
- 3
- 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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