Question

x + y = 7
y + z = 5
z + x = - 4
Решите систему уравнений

Answer 1

$\left\{ \begin{aligned} x+y&=7\\ y+z & = 5\\ z+x&=-4.\\ \end{aligned} \right. =\ \textgreater \ \left\{ \begin{aligned} x+y&=7\\ y+z & = 5\\ -y+z&=-11.\\ \end{aligned} \right. =\ \textgreater \ \left\{ \begin{aligned} x+y&=7\\ y+z & = 5\\ 2z &=-6.\\ \end{aligned} \right. =\ \textgreater \ \left\{ \begin{aligned} x+y&=7\\ y+z & = 5\\ z=&=-3.\\ \end{aligned} \right.$

$=\ \textgreater \ \left\{ \begin{aligned} x+y&=7\\ y & = 8\\ z&=-3.\\ \end{aligned} \right. =\ \textgreater \ \left\{ \begin{aligned} x&=-1\\ y & = 8\\ z&=-3.\\ \end{aligned} \right.$