\(\left(n-4\right)⋮\left(n-1\right)\Rightarrow\left(n-1-3\right)⋮\left(n-1\right)\)
\(Mà\left(n-1\right)⋮\left(n-1\right)\Rightarrow-3⋮\left(n-1\right)\Rightarrow n-1\inƯ\left(-3\right)=\left\{\pm1;\pm3\right\}\Rightarrow n\in\left\{-2;0;2;4\right\}\)
\(\dfrac{n-4}{n-1}=\dfrac{n-1}{n-1}-\dfrac{4}{n-1}\)
Nhận xét:
\(\left(n-1\right)⋮\left(n-1\right)\\ \left(n-4\right)⋮\left(n-1\right)\\ \Rightarrow4⋮\left(n-1\right)\\ Hay.\left(n-1\right)\inƯ_{\left(4\right)}=\left\{-4;-2;-1;1;2;4\right\}\\ \Rightarrow n\in\left\{-3;-1;0;2;3;5\right\}\)
(n−4)⋮(n−1)⇒(n−1−3)⋮(n−1)(n−4)⋮(n−1)⇒(n−1−3)⋮(n−1)
Mà(n−1)⋮(n−1)⇒−3⋮(n−1)⇒n−1∈Ư(−3)={±1;±3}⇒n
∈{−2;0;2;4}
(n−4)⋮(n−1)⇒(n−1−3)⋮(n−1)(n−4)⋮(n−1)⇒(n−1−3)⋮(n−1)
Mà(n−1)⋮(n−1)⇒−3⋮(n−1)⇒n−1∈Ư(−3)={±1;±3}⇒n
∈{−2;0;2;4}