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3 and 4 .Determinants and Matrices
hard
સમીકરણ $\left| {\begin{array}{*{20}{c}}
x&{ - 6}&{ - 1}\\
2&{ - 3x}&{x - 3}\\
{ - 3}&{2x}&{x = 2}
\end{array}} \right| = 0$ ના વાસ્તવિક બીજનો સરવાળો મેળવો.
A
$-4$
B
$0$
C
$6$
D
$1$
(JEE MAIN-2019)
Solution
By expansion, we get
$ – 5{x^3} + 30x – 30 + 5x = 0$
$ \Rightarrow – 5{x^3} + 35x – 30 = 0$
$ \Rightarrow {x^3} – 7x + 6 = 0$, All roots srea real
So, sum of roots $=0$
Standard 12
Mathematics