Question

реши систему уравнений методом подстановки.
{-z-2y+1=4 {z= -5-y
РЕШИТЕ пожалуйста!!!
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Answer 1

$\left\{\begin{array}{l}-z-2y+1=4\\z=-5-y\end{array}\right\; \; \left\{\begin{array}{l}-(-5-y)-2y=3\\z=-5-y\end{array}\right\; \; \left\{\begin{array}{l}5-y=3\\z=-5-y\end{array}\right\\\\\\\left\{\begin{array}{l}y=2\\z=-5-2\end{array}\right\; \; \left\{\begin{array}{l}y=2\\z=-7\end{array}\right\qquad \Rightarrow \; \; \; (2;-7)$