Question

решите систему уравнений {ху-у=24, х-3у=7​

Answer 1

$\left\{\begin {array}{ccc}xy-y=24 \\\\x-3y=7 \end {array } \right \to \left\{\begin {array}{ccc}xy-y=24 \\\\x=7+3y \end {array } \right \to \\\\\\(7+3y)y-y=24 \\\\7y+3y^2-y=24 \\\\3y^2+6y-24=0 \ \ |\div3 \\\\y^2+2y-8=0 \\\\ \displaystyle \left \{ {{y_1+y_2=-2} \atop {y_1y_2=-8 }} \right. \to y_1=-4 \ \ ; \ \ y_2=2 \\\\. \qquad \qquad \qquad \qquad x_1=-5 \ \ ; \ \ x_2=13$