a: Để y có nghĩa thì x-1<>0
hay x<>1
b: \(f\left(-2\right)=\dfrac{5}{-2-1}=\dfrac{-5}{3}\)
\(f\left(2\right)=\dfrac{5}{2-1}=5\)
\(f\left(\dfrac{1}{3}\right)=\dfrac{5}{\dfrac{1}{3}-1}=\dfrac{5}{-\dfrac{2}{3}}=5\cdot\dfrac{-3}{2}=-\dfrac{15}{2}\)
c: f(x)=-1
=>x-1=-5
hay x=-4
f(x)=1
=>x-1=5
=>x=6