Lg(x^2-5x+68)=2(lg16-lg2)

lg16-lg2=lg16/2=lg8
lg(a/b)=lga-lgb
lg(x^2-5x+68)=lg8^2
2lg8=lg8^2
x^2-5x+68=64
x^2-5x+4=0
x=(5+-√(25-16))/2
x=(5+-3)/2
x1=(5-3)/2=1
x2=(5+3)/2=4