Question

The roots of the equation $\left| \begin{matrix} 0 & x & 16 \\ x & 5 & 7 \\ 0 & 9 & x \end{matrix} \right| = 0$are .

• A. $0,12,12$
• B. 0, 12, –12
• C. 0, 12, 16
• D. 0, 9, 16

Answer 1

Answer: (B)

0, 12, –12

Answer 2

$\left| \begin{matrix} 0 & x & 16 \\ x & 5 & 7 \\ 0 & 9 & x \end{matrix} \right| = 0$

By expanding, we get $- x(x^{2} - 144) = 0$

$x = 0$ or $x^{2} = 144$ $\Rightarrow$ $x = \pm 12$

So, $x = 0$, $12, - 12$.