Ответ: [tex] \left \{ {{y=9-x} \atop {xy=8}} ight. [/tex] ⇔[tex] \left \{ {{y=9-x} \atop {9x- x^{2} =8}} ight. [/tex] ⇒ [tex] \left \{ {{y=9-x} \atop { x^{2} -9x+8=0}} ight. [/tex] ⇔ [tex] \left \{ {{y=8; 1} \atop {x=1; 8}} ight. [/tex]Ответ: (1;8), (8;1).
Ответ:
х=9-у
(9-у)*у=89у-у2-8=0
-у2+9у-8=0
Д=81-32=49
У1= (-9+7): (-2)=1
У2=(-9-7): (-2)= 8
Х1=9-1=8
Х2=9-8=1