Question

Решите систему уравнений: 2x-y=5; x^2+y+2=0

Answer 1

2x-y=5; x^2+y+2=0
2x-5=y ; x^2+y+2=0
x^2+2x-5+2=0
2x-+2x-3=0
D=4+12=16
x1=-3
x2=1

x=-3 y=1   или   x=1 y=-3

Answer 2

Ответ:

(1;-3), (-3;-11).

Объяснение:

$left { begin{array}{lcl} {{2x-y=5,} \ {x^{2} +y+2=0;}} end{array} right.Leftrightarrow left { begin{array}{lcl} {{y=2x-5,} \ {x^{2} +2x-5+2=0;}} end{array} right.Leftrightarrowleft { begin{array}{lcl} {{y=2x-5,} \ {x^{2}+2x-3=0;}} end{array} Leftrightarrowright.$

$left { begin{array}{lcl} {{y=2x-5,} \ {left [ begin{array}{lcl} {{x=1,} \ {x=-3;}} end{array} right.}} end{array} right.Leftrightarrow left left [begin{array}{lcl} {{left { begin{array}{lcl} {{x=1,} \ {y=-3;}} end{array} right.} \ {left { begin{array}{lcl} {{x=-3,} \ {y=-11.}} end{array} right.}} end{array} right.$