Đ/K : \(n\ne\frac{1}{2}\)
Để \(4n-5⋮2n-1\)
\(\Leftrightarrow4n-2-3⋮2n-1\)
\(\Leftrightarrow2\left(2n-1\right)-3⋮2n-1\)
\(\Leftrightarrow3⋮2n-1\)
\(\Leftrightarrow2n-1\inƯ\left(3\right)\)
\(\Leftrightarrow2n-1\in\left\{1;-1;3;-3\right\}\)
\(\Leftrightarrow2n\in\left\{2;0;4;-2\right\}\)
\(\Leftrightarrow n\in\left\{1;0;2;-1\right\}\)
Mà \(n\in N\)
\(\Rightarrow n\in\left\{1;0;2\right\}\)
Vậy \(n\in\left\{1;0;2\right\}\)
~ Ủng hộ nha
\(4n-5⋮2n-1\)
\(4n-1-4⋮2n-1\)
Mà \(4n-1⋮2n-1\Rightarrow4⋮2n-1\)
\(\Rightarrow2n-1\inƯ\left(4\right)=\left\{1;2;4;-1;-2;-4\right\}\)
Ta có bảng :
| 2n-5 | 1 | 2 | 4 | -1 | -2 | -4 |
| n | 3 | 3,5 | 4,5 | 2 | 1,5 | 0,5 |
Mà n là số tự nhiên => n thuôc {3; 2 }
Vậy, ......
Bạn Bonking sai rồi nhé :
\(4n-2=2\left(2n-1\right)\)
\(\Rightarrow4n-2⋮2n-1\)
