Lg (x²+19)-lg (x+1)=1

Question

Lg (x²+19)-lg (x+1)=1

Answer 1

ОДЗ x>-1
lg(x²+19)/(x+1)=1
(x²+19)/(x+1)=10
x²+19=10x+10
x²-10x+9=0
x1+x2=10 U x1*x2=9
x1=1 U x2=9