Question

решите систему уравнений:
x-y=2
xy=15

Answer 1

$\left \{ {{x-y=2} \atop {yx=15}} \right. \Longrightarrow \left \{ {{x-y=2} \atop {y=\frac{15}{x}}} \right. \\\\x-\frac{15}{x}-2=0\\\\\frac{x^2-15-2x}{x}=0\\\\OD3:x\neq0\\\\x^2-2x-15=0\\D=(-2)^2-4*(-15)=64\\\sqrt{64}=8\\\\x_1=\frac{2-8}{2}=-3\\\\x_2=\frac{2+8}{2}=5\\\\-3-y_1=2\\y_1=-5\\\\5-y_2=2\\y_2=3$

Ответ: (5; 3); (-3; -5).