Question

Сколько решений имеет система уравнений x^2+y^2=9 3-xy=0

Answer 1

$\left \{ {{x^2+y^2=9} \atop {3-xy=0}} \right \left \{ {{x^2+y^2=9} \atop {-xy=-3}} \right.\left \{ {{x^2+y^2=9} \atop {y=3/x}} \right. x^2+(3/x)^2=9\ x^2+9/x^2= 9 | *x^2 x^4 + 9 = 9x^2 x^4 -9x^2+ 9 = 0 x^2=a a^2 -9a+9=0 D=81-36=45. a1=(9+\sqrt{45})/2 = (9+ 6.7) / 2 = 7.85 .a2 = (9-\sqrt{45})/2 = (9- 6.7) / 2= 1.15. x^2 = 7.85 x\approx2.8 x\approx-2.8x^2 = 1.15.x\approx1.07 x\approx-1.07$$\left \{ {{x^2+y^2=9} \atop {3-xy=0}}.\right \left \{ {{x^2+y^2=9} \atop {-xy=-3}}.\right.\left \{ {{x^2+y^2=9} \atop {y=3/x}}.\right. x^2+(3/x)^2=9\.x^2+9/x^2= 9 | *x^2.x^4 + 9 = 9x^2.x^4 -9x^2+ 9 = 0.x^2=a.a^2 -9a+9=0.D=81-36=45.a1=(9+\sqrt{45})/2 = (9+ 6.7) / 2 = 7.85.a2 = (9-\sqrt{45})/2 = (9- 6.7) / 2= 1.15.x^2 = 7.85 x\approx2.8 x\approx-2.8x^2 = 1.15.x\approx1.07 x\approx-1.07$.ответ: система имеет 4 решения.