Question

Помогите решить плиз

Answer 1

Ответ:

Пошаговое объяснение:

$\left[\begin{array}{ccc}x&2&3\\-4&-2x&5\\6&6&7\end{array}\right] =0;\\\left[\begin{array}{ccc}x&2&3\\-4&-2x&5\\6&6&7\end{array}\right] =x*(-2x)*7+2*5*6+(-4)*6*3-3*6*(-2x)-5*6*x-2*(-4)*7=-14x^{2} +60-72+36x-30x+56=-14x^{2} +6x+44=0$

$-14x^{2} +6x+44=0;\\7x^{2} -3x-22=0;\\D=3^{2} +4*7*22=9+616=625;\\x_{1} =\frac{3+25}{2*7} =\frac{28}{14} =2;\\x_{2} =\frac{3-25}{2*7} =\frac{-22}{14} =-\frac{11}{7}\\x_{1}=2;\\x_{2} =-\frac{11}{7}$