This summer I spent with my grandmother. We had fun, and not only rested well and worked, helped my beloved grandmother. We went to the river, there were a lot of people and I met a company of boys. We still communicate despite the distance. When I arrived home to my parents, I saw that my parents decided to surprise me by putting a huge pool that was the best summer of my life
Вот такой ответ. Ход решения , к сожалению,показать не смогу.
Lg(x^2+2x-7) - lg(x-1)=0
lg(x^2+2x-7)=lg(x-1)
ОДЗ: x-1>0; x>1
x^2+2x-7=x-1
x^2+2x-7-x+1=0
x^2+x-6=0
D=1^2-4*1*(-6)=25
x1=(-1-5)/2=-3
x2=(-1+5)/2=2
Ответ: 2
27x*1/9+x=3x+x=4x
75x*1/25+x=3x+x=4x