Задача с уравнение

[Гост]

Моля, помогнете!

[ammornil]

Нещо такова, предполагам...

[tex]A=\begin{Vmatrix} 4 & 5 & 2 \\ 0 & 7 & -4 \\ 1 & -3 & 3 \end{Vmatrix}[/tex], [tex]B=\begin{Vmatrix} 3 \\ -5 \\ 4 \end{Vmatrix}[/tex]

а) [tex]M_{2,1}= \begin{vmatrix} 5 & 2 \\ -3 & 3 \end{vmatrix}=5.3-2.(-3)=15+6=21[/tex]

б) [tex]A_{2,3}=(-1)^{2+3}.M_{2,3}=- \begin{vmatrix} 4 & 5 \\ 1 & -3 \end{vmatrix}=-[4.(-3)-5.1]=-(-12-5)=17[/tex]

[tex]A_{3,3}=(-1)^{3+3}.M_{3,3}= \begin{vmatrix} 4 & 5 \\ 0 & 7 \end{vmatrix}=4.7-5.0=28[/tex]

в) [tex]\Delta = \begin{vmatrix} 4 & 5 & 2 \\ 0 & 7 & -4 \\ 1 & -3 & 3 \end{vmatrix} =4.7.3+2.0.(-3)+1.5.(-4)-2.7.1-0.5.3-4.(-4).(-3)[/tex]
[tex]\Delta = 84+0-20-14-0-48=84-82=2[/tex]

[tex]\Delta _{1} = \begin{vmatrix} 3 & 5 & 2 \\ -5 & 7 & -4 \\ 4 & -3 & 3 \end{vmatrix} = 3.7.3+5.4.(-4)+2.(-5).(-3)-2.7.4-3.5.(-5)-3.(-3).(-4)=[/tex]
[tex]\Delta _{1} = 63-80+30-56+75-36= 168-172=-4[/tex]

[tex]\Delta _{2} = \begin{vmatrix} 4 & 3 & 2 \\ 0 & -5 & -4 \\ 1 & 4 & 3 \end{vmatrix} = 4.(-5).3+0.4.2+1.3.(-4)-2.(-5).1-4.4.(-4)-3.0.3 =[/tex]
[tex]\Delta _{2} = -60+0-12+10+64-0 = 74-72=2[/tex]

[tex]\Delta _{3} = \begin{vmatrix} 4 & 5 & 3 \\ 0 & 7 & -5 \\ 1 & -3 & 4 \end{vmatrix} = 4.7.4+1.5.(-5)+3.0.(-3)-3.7.1-4.0.5-4.(-3).(-5) =[/tex]
[tex]\Delta _{3} = 112-25+0-21-0-60= 112-106=6[/tex]

[tex]x_{1}=\frac{\Delta _{1}}{\Delta}=\frac{-4}{2}=-2;[/tex] [tex]x_{2}=\frac{\Delta _{2}}{\Delta}=\frac{2}{2}=1;[/tex] [tex]x_{3}=\frac{\Delta _{3}}{\Delta}=\frac{6}{2}=3;[/tex]

[Гост]

Благодаря, от сърце.