Question

даю 90 баллов пж напишите
решите систему уравнений
{x+y^2=3
{xy^2=4

Answer 1

$\displaystyle\left \{ {{x+y^2=3} \atop {xy^2=4}} \right. \Leftrightarrow \left \{ {{x=3-y^2} \atop {xy^2=4}} \right. \Leftrightarrow (3-y^2)y^2=4;~3y^2-y^4=4~;~3y^2-y^4-4=0~;~-y^4+3y^2-4=0\Leftrightarrow t=y^2\Rightarrow -t^2+3t-4=0~;~D=3^2-4*(-1)*(-4)=9-16-7\Rightarrow y\notin\mathbb R\Longrightarrow (x;y)\notin\mathbb R^2.$