[tex] \left \{ {{2(3x-y)-5=2x-3y} \atop {5-(x-2y)=4y+16}} \right. \\ \Leftrightarrow
\left \{ {{6x-2y-5=2x-3y} \atop {5-x+2y=4y+16}} \right. \\ \Leftrightarrow
\left \{ {{4x+y-5=0} \atop {-x=2y+11}} \right.
\\ \Leftrightarrow
\left \{ {{4x+y-5=0} \atop {x=-2y-11}} \right. \\ \Leftrightarrow
\left \{ {{4(-2y-11)+y-5=0} \atop {x=-2y-11}} \right. \\ \Leftrightarrow
\left \{ {{-8y-44+y-5=0} \atop {x=-2y-11}} \right. \\ \Leftrightarrow
\left \{ {{-7y=49} \atop {x=-2y-11}} \right. [/tex]
[tex]\\ \Leftrightarrow
\left \{ {{y=-7} \atop {x=-2y-11}} \right. \\ \Leftrightarrow
\left \{ {{y=-7} \atop {x=-2\cdot (-7)-11}} \right.
\\ \Leftrightarrow
\left \{ {{y=-7} \atop {x=3}} \right. [/tex]
A doua varianta:
[tex]\left \{ {{2(3x-y)-5=2x-3y} \atop {5-(x-2y)=4y+16}} \right. \\ \Leftrightarrow \left \{ {{6x-2y-5=2x-3y} \atop {5-x+2y=4y+16}} \right. \\ \Leftrightarrow \left \{ {{4x+y-5=0 \ |\cdot 2} \atop {-x-2y-11=0}} \right. \\
--------\\
7x\ / \ -21=0 \Leftrightarrow 7x=21 \Leftrightarrow x=3\\
12+y-5=0 \Leftrightarrow y+7=0 \Leftrightarrowy=-7\\
\Leftrightarrow \left \{ {{x=3} \atop {y=-7}} \right. [/tex]
