Question

Решите способом подстановки

Answer 1

$\displaystyle \left \{ {{y=5-x} \atop {3x-y=11}} \right.\\ 3x-(5-x)=11\\x=4\\y=5-4\\y=1\\(x,y)=(4,1)$

Answer 2

$\displaystyle\bf\\\left \{ {{y=5-x} \atop {3x-y=11}} \right. \\\\\\\left \{ {{y=5-x} \atop {3x-(5-x)=11}} \right. \\\\\\\left \{ {{y=5-x} \atop {3x-5+x=11}} \right.\\\\\\\left \{ {{y=5-x} \atop {4x=16}} \right. \\\\\\\left \{ {{x=4} \atop {y=5-4}} \right. \\\\\\\left \{ {{x=4} \atop {y=1}} \right. \\\\\\Otvet: \ (4 \ ; \ 1)$