[tex] \left \{ {{x+y=12} \atop {xy=35}} ight. [/tex]

x=12-y(12-y)*y=35x=12-y12y-y²=35x=12-yy²-12y+35=0D=144-140=4y1= (12-2)/2= 5y2= (12+2)/2= 7x1= 7x2= 5Ответ: (7;5), (5;7)