Question

способом подстановки {3х -2у=5
{Х+2у=15
Способ сложения {2х+11у=15
{10х-11у=9

Answer 1

1)
$\displaystyle \left \{ {{3x-2y=5} \atop {x+2y=15}} \right. < = > \left \{ {{3(15-2y)-2y=5} \atop {x=15-2y}} \right. < = > \left \{ {{45-6y-2y=5} \atop {x=15-2y}} \right. < = > \left \{ {{-8y=-40|:(-8)} \atop {x=15-2y}} \right. < = > \left \{ {{y=5} \atop {x=15-2*5}} \right. < = > \left \{ {{y=5} \atop {x=5}} \right.$
Ответ: (х;у) = (5;5)

2)
$\displaystyle +\left \{ {{2x+11y=15} \atop {10x-11y=9}} \right. < = > 12x=24|:12 < = > x=2$
$\displaystyle 2*2+11y=15 < = > 11y=15-4|:11 < = > y=1$
Ответ: (х;у) = (2;1)