[tex] \left \{ {{x+y=7} \atop {lg x + lg y=1}} ight. [/tex]

Помогите.

x + y = 7lg (xy) = 1x > 0y > 0x + y = 7xy = 10x > 0y > 0x = 2, y = 5x = 5, y = 2Ответ: (2; 5), (5; 2).