JEE MAIN - Mathematics (2022 - 25th July Evening Shift - No. 2)
The number of real values of $$\lambda$$, such that the system of linear equations
2x $$-$$ 3y + 5z = 9
x + 3y $$-$$ z = $$-$$18
3x $$-$$ y + ($$\lambda$$2 $$-$$ | $$\lambda$$ |)z = 16
has no solutions, is
0
1
2
4
Explanation
$$\Delta = \left| {\matrix{ 2 & { - 3} & 5 \cr 1 & 3 & { - 1} \cr 3 & { - 1} & {{\lambda ^2} - |\lambda |} \cr } } \right| = 2\left( {3{\lambda ^2} - 3|\lambda | - 1} \right) + 3\left( {{\lambda ^2} - |\lambda | + 3} \right) + 5( - 1 - 9)$$
$$ = 9{\lambda ^2} - 9|\lambda | - 43$$
$$ = 9|\lambda {|^2} - 9|\lambda | - 43$$
$$\Delta = 0$$ for 2 values of $$|\lambda |$$ out of which one is $$-\mathrm{ve}$$ and other is $$+\mathrm{ve}$$
So, 2 values of $$\lambda$$ satisfy the system of equations to obtain no solution.
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