Question

Реши методом алгебраического сложения сист. Ур.
{5у-4х=-7
{5у+х=2

Answer 1

$\displaystyle\bf\\\left \{ {{5y-4x=-7 \ |\cdot(-1)} \atop {5y+x=2}} \right. \\\\\\+\left \{ {{-5y+4x=7} \atop {5y+x=2}} \right. \\---------\\5x=9\\\\x=1,8\\\\5y=2-x=2-1,8=0,2\\\\y=0,2:5=0,04\\\\\\Otvet: \ (1,8 \ ; \ 0,04)$