Б) lg(x^2-9)=lg(4x+3) -> x^2-9=4x+3 - > x^2-4x-12=0 x1=6 x2=-2
в) 2log2(-x)=1+log2(x+4) -> log2(x^2)=log2(2x+8) -> x^2-2x-8=0 x1=4 x2=-2
г) (log5(x))^2+log5(x)-2=0
] log5(x)=t
t^2+t-2=0 -> t1=-2 t=-1
log5(x)=-2 -> log5(x)=log5((5)^(-2)) -> x=5^-2 -> x=1/25
log5(x)=-1 -> log5(x)=log5(5^-1) -> x=5^-1 -> x=1/5