Log4(x-1)+Log4(x+11)=3

Question

Log4(x-1)+Log4(x+11)=3

Answer 1

Log4 (x-1)(x+11)=Log4 64, (x-1)(x+11)=64, x^2+10x-11-64=0, x^2+10x-75=0. D=100-4*1*(-75)=100+300=400. x1=(-10-20)/2, x2=(-10+20)/2. x1=-15, x2=5. Ответ: x=5.