Question

Решите способом подстановки систему уравнений .
{Х+5у=0
{3х+7у-16=0

{7х-у=0
{3х-у+12=0

Answer 1

1.
$x + 5y = 0 \\ 3x +7y = 16$
$x = - 5y \\ - 15y + 7y = 16$
$- 8y = 16$
$y = - 2 \\ x = 10$
2.
$7x - y = 0 \\ 3x - y = - 12$
$y= 7x \\ - 4x = - 12$
$x = 3 \\ y = 21$