MCQ
Evaluate the following determinant:
$
\left|\begin{array}{cc}
x & -5 x \\
1 & x+10
\end{array}\right|
$
  • A
    $5 x^2+4$
  • $x(x+15)$
  • C
    $x(x-15)$
  • D
    $x(15-x)$

Answer

Correct option: B.
$x(x+15)$
(b): We have, $\left|\begin{array}{cc}x & -5 x \\ 1 & x+10\end{array}\right|=x(x+10)+5 x$ $=x^2+10 x+5 x=x^2+15 x=x(x+15)$

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