Question

If $x^3-2x^2-9x+18=0$ and $A=\left|\begin{array}{ccc}1& 2& 3\\ 4& x& 6\\ 7& 8& 9\end{array}\right|$ then the maximum value of $A$ is

• A. 96
• B. 36
• C. 24
• D. 120

Answer 1

Answer: (A)

$(x-2)\left(x^2-9\right)=0$
$x=2,3,-3$
$f(x)=|A|=-12x+60$
Max value at $x=-3$
$\therefore |A|=96$