Question

Tìm x biết

x - 5 chia hết cho x - 2

Answer 1

x-5⋮x-2

=> (x-2)-3⋮x-2

Vi x-2⋮x-2 => -3⋮x-2 => x-2∈U(-3)=(1,3,-1,-3)

=> x=3,5,1,-1

Answer 2

Mình còn cách khác :

Vì \(x-5⋮x-2\Rightarrow x-5-\left(x-2\right)⋮x-2\)

\(\Rightarrow x-5-x+2⋮x-2\)

\(\Rightarrow\left(x-x\right)-\left(5-2\right)⋮x-2\)

\(\Rightarrow0-3⋮x-2\)

\(\Rightarrow-3⋮x-2\)

\(\Rightarrow x-2\inƯ\left(-3\right)=\left\{1;-1;3;-3\right\}\)

x - 2	1	-1	3	-3
x	3	1	5	-1

Vậy \(x\in\left\{3;1;5;-1\right\}\)