Đáp án:
a. \(\left\{\begin{matrix}
x=1 & \\
y=2& \\
z=-3 &
\end{matrix}\right.\)
b. \( \left\{\begin{matrix}
x=1 & \\
y=2 & \\
z=-3
\end{matrix}\right.\)
Giải thích các bước giải:
a. \(\left\{\begin{matrix} x+y+z=0 & \\ x+y=3 & \end{matrix}\right.\to z=-3\)
\(\left\{\begin{matrix} x+y+z=0 & \\ y+z=-1& \end{matrix}\right.\to x=1\)
mà $x+y+z=0\to 1+y-3=0\to y=2$
b. \(\left\{\begin{matrix} \left\{\begin{matrix} x+y=3 & \\ y+z=-1\ \end{matrix}\right. \to x+y-y-z=4\to x-z=4& \\ x+z=-2& \end{matrix}\right.\rightarrow \left\{\begin{matrix} x=1 & \\ z=-3 & \end{matrix}\right.\to y=2\)
\(\rightarrow \left\{\begin{matrix}
x=1 & \\
y=2 & \\
z=-3
\end{matrix}\right.\)
