• Решить систему
    X^2+y^2=37
    Xy=6

Ответы 1

  •  \left \{ {{x^2+y^2=37} \atop {xy=6}} ight.  \left \{ {{x^2+y^2=37} \atop {y= \frac{6}{x} }} ight. \left \{ {{x^2+( \frac{6}{x})^2=37} \atop {y= \frac{6}{x} }} ight.   \left \{ {{x^4-37x^2+36=0} \atop {y= \frac{6}{x}}} ight.  \\  \\ t=x^2,t \geq 0 \\  \\ t^2-37t+36=0;D=1369-144=1225=35^2 \\  \\ 1)   t_{1} =(37+35)/2=36=6^2; \left \{ {{ x_{1}=6 } \atop { y_{1} =1}} ight. ; \left \{ {{ x_{2}=-6 } \atop { y_{2} =-1}} ight. \\  \\
2)   t_{2} =(37-35)/2=1; \left \{ {{ x_{3}=1 } \atop { y_{3} =6}} ight. ; \left \{ {{ x_{4}=-1 } \atop { y_{4} =-6}} ight. \\  \\  otvet:(6;1)(-6;-1)(1;6)(-1;-6) \left \{ {{x^2+y^2=37} \atop {xy=6}} ight.  \left \{ {{x^2+2xy+y^2-2xy=37} \atop {xy=6}} ight.  \left \{ {{(x+y)^2-2xy=37} \atop {xy=6}} ight. \left \{ {{(x+y)^2-12=37} \atop {xy=6}} ight. \\  \\ \left \{ {{(x+y)^2-49=0} \atop {xy=6}} ight. \left \{ {{(x+y+7)(x+y-7)=0} \atop {xy=6}} ight.  \\  \\ 1)\left \{ {{x+y+7=0} \atop {xy=6}} ight. \left \{ {{y=-x-7} \atop {xy=6}} ight. \left \{ {{y=-x-7} \atop {x(-x-7)=6}} ight.\left \{ {{y=-x-7} \atop {x^2+7x+6=0}} ight.  \\  \\ D=49-24=25 \left \{ {{ x_{1}=(-7-5)/2=-6 } \atop { y_{1}=6-7=-1 }} ight.  \left \{ {{ x_{2}=(-7+5)/2=-1 } \atop { y_{1}=1-7=-6 }} ight.  \\  \\ 2)\left \{ {{x+y-7=0} \atop {xy=6}} ight. \left \{ {{y=7-x} \atop {xy=6}} ight. \left \{ {{y=7-x} \atop {x(7-x)=6}} ight.\left \{ {{y=7-x} \atop {x^2-7x+6=0}} ight. \\ D=25 \\  \\ \left \{ {{ x_{3}=(7-5)/2=1 } \atop { y_{3}=7-1=6 }} ight.  \left \{ {{ x_{4}=(7+5)/2=6} \atop { y_{4}=7-6=1 }} ight.  \\  \\
    • Автор:

      kenzie
    • 5 лет назад
    • 0
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