Question

решить систему уравнений
x+y=7
lg x+lg y=1

Answer 1

{x=7-y. ОДЗ: х>0, у>0 {x=7-y. {x=7-y lg(7-y)+lay=1, lg((7-y)*y)=1, 7y-y²=10 y²-7y+10=0, y₁=2, y₂=5 x₁=5, x₂=2