Tìm n ∈ Z để 2n² + 5n – 1 chia hết cho 2n – 1 19/11/2021 Bởi Bella Tìm n ∈ Z để 2n² + 5n – 1 chia hết cho 2n – 1
`2n^² + 5n – 1vdots2n-1` `ton^²-n +6n-3+2vdots2n-1` `ton(2n-1) +3(2n-1)+2vdots2n-1` `to(2n-1) (n+3)+2vdots2n-1` `to2vdots2n-1` `to2n-1\in Ư_((2))={+-1;+-2}` `to2n\in{-1;0;2;3}` `tonin{(-1)/2;0;1;3/2}` `text(và )ninmathbbZ` `tonin{0;1}text( thì )2n^2+5-1vdots2n-1` Bình luận
`2n^² + 5n – 1vdots2n-1`
`ton^²-n +6n-3+2vdots2n-1`
`ton(2n-1) +3(2n-1)+2vdots2n-1`
`to(2n-1) (n+3)+2vdots2n-1`
`to2vdots2n-1`
`to2n-1\in Ư_((2))={+-1;+-2}`
`to2n\in{-1;0;2;3}`
`tonin{(-1)/2;0;1;3/2}`
`text(và )ninmathbbZ`
`tonin{0;1}text( thì )2n^2+5-1vdots2n-1`