Question

Tìm số nguyên n:

a) 2n-3⋮n+1

b) n+2⋮2n-3

c) 6n+2⋮2n-1

Làm 1 câu cũng dc ạ!!

Answer 1

Câu c/

$6n+2\vdots 2n-1$

$3(2n-1)+5\vdots 2n-1$

$\Rightarrow 5\vdots 2n-1$

$\Rightarrow 2n-1\in Ư(5)$

$\Rightarrow 2n-1\in \left\{1; -1; 5; -5\right\}$

$\Rightarrow n\in \left\{1; 0; 3; -2\right\}$

Answer 2

Câu a/

$2n-3\vdots n+1$

$2(n+1)-5\vdots n+1$

$5\vdots n+1$

$\Rightarrow n+1\in Ư(5)$

$\Rightarrow n+1\in \left\{1; -1; 5; -5\right\}$

$\Rightarrow n\in \left\{0; -2; 4; -6\right\}$

Answer 3

Câu b/

$n+2\vdots 2n-3$

$\Rightarrow 2(n+2)\vdots 2n-3$

$\Rightarrow 2n-3+7\vdots 2n-3$

$\Rightarrow 7\vdots 2n-3$
$\Rightarrow 2n-3\in Ư(7)$

$\Rightarrow 2n-3\in \left\{1; -1; 7; -7\right\}$

$\Rightarrow n\in \left\{2; 1; 5; -2\right\}$