Question

Решите неравенство x-2y=1
xy+y=12

Answer 1

$x-2y=1\ xy+y=12\\ x-2y=1\ xy+y+x+1=13+x\ \ x-2y=1\ (x+1)(y+1)=13+x\ \ x=1+2y\ (2+2y)(y+1)=14+2y\ 2(y+1)^2=2(7+y)\ (y+1)^2=7+y\ y^2+2y+1=7+y \ y^2+y-6=0\ D=5^2\ y=2\ y=-3\ x=5\ y=-5$