Помогите log(3x+1)+log10x=1

lg(3x +1) + lg(x) = 1  ОДЗ: x> 0lg(3x+1)*(x) = 13x^2 + x = 10^13x^2 + x - 10 = 0   D = 1+ 4*3*10 = 121x1 (-1 - 11)/6x1 = -2 не удовлетворяет ОДЗx2 = (-1 + 11)/6x2 = 5/3х2 = 1(2/3)Ответ: х = 1(2/3)