A) \[x=\frac{11\pm \sqrt{5}}{2}\]
B) \[x=\frac{9\pm \sqrt{5}}{2}\]
C) \[x=\frac{11\pm \sqrt{3}}{2}\]
D) \[x=\frac{9\pm \sqrt{3}}{2}\]
Correct Answer: A
Solution :
[a] \[A=\left[ \begin{matrix} 1 & 3 & 2 \\ 1 & x-1 & 1 \\ 2 & 7 & x-3 \\ \end{matrix} \right]\] \[\left| A \right|=1[(x-1)(x-3)-7]-3[(x-3)-2]\] \[+2[7-2(x-1)]\] \[={{x}^{2}}-11x+29\] If inverse will not exist then \[\left| A \right|=0\] \[{{x}^{2}}-11x+29=0\] \[x=\frac{11\pm \sqrt{5}}{2}\]
You need to login to perform this action.
You will be redirected in
3 sec
