Question

x - y = 7
xy = -10
система​​

Answer 1

$\displaystyle\bf\\1)\\\\\left \{ {{x-y=7} \atop {xy=-10}} \right. \\\\\\\left \{ {{x=y+7} \atop {(y+7)\cdot y=-10}} \right.\\\\\\\left \{ {{x=y+7} \atop {y^{2} +7y+10=0}} \right. \\\\\\\left \{ {{x=y+7} \atop {\left[\begin{array}{ccc}y_{1} =-2\\y_{2} =-5\end{array}\right}} \right. \\\\\\\left[\begin{array}{ccc}\left \{ {{x_{1} =-2+7} \atop {y_{1} =-2}} \right. \\\left \{ {{x_{2} =-5+7} \atop {y_{2} =-5}} \right. \end{array}\right$

$\displaystyle\bf\\\left[\begin{array}{ccc}\left \{ {{x_{1} =5} \atop {y_{1} =-2}} \right. \\\left \{ {{x_{2} =2} \atop {y_{2} =-5}} \right. \end{array}\right\\\\\\Otvet: \ (5 \ ; \ -2) \ , \ (2 \ ; \ -5)$