''Системи линейни уравнения с две неизвестни''

[Koceto]

|5x+4=6x-y
|6x+y=21+4y

[Xixibg]

[tex]x=3 ; y=-1[/tex]

[Гост]

x=3 ; y=-1



dai malko po podrobnao

5x+4=6x-y => 5x-6x+y=-4 => -x+y=-4/ :3 =>-3x+3y=-12 sega sukrashtavame (+3y -3y)
6x+y=21+4y => 6x+y-4y=21=> 6x-3y=21 =>6x-3y=21

3x=9 -x+y=-4
x=3 -3+y=-4
y=-1 x=3 ;y=-1

[Xixibg]

[tex]\begin{tabular}{|l}5x+4=6x-y ; =>y=x-4\\6x+y=21+4y ; =>y=\frac{6x-21}{3}=2x-7\end{tabular}[/tex]

[tex]=>x-4=2x-7 ; =>x=3 ; =>y=-1[/tex]