Question

( x+y=7
(x - y = 1
Розв'язати підстановкою

Answer 1

$\displaystyle\bf\\\left \{ {{x+y=7} \atop {x-y=1}} \right. \\\\\\\left \{ {{x=y+1} \atop {y+1+y=7}} \right. \\\\\\\left \{ {{x=y+1} \atop {2y+1=7}} \right. \\\\\\\left \{ {{x=y+1} \atop {2y=7-1}} \right. \\\\\\\left \{ {{x=y+1} \atop {2y=6}} \right. \\\\\\\left \{ {{x=3+1} \atop {y=3}} \right. \\\\\\\left \{ {{x=4} \atop {y=3}} \right. \\\\\\Otvet \ : \ (4 \ ; \ 3)$