\(-7⋮x+3\\ \Rightarrow\left(x+3\right)\inƯ_{\left(-7\right)}=\left\{-7;-1;1;7\right\}\\ \Rightarrow x\in\left\{-10;-4;-2;4\right\}\)
\(\Leftrightarrow x+3\in\left\{1;-1;7;-7\right\}\)
hay \(x\in\left\{-2;-4;4;-10\right\}\)
-7 \(⋮\) x + 3 => x + 3 \(\in\) Ư(-7) = { -1 , 1 , -7 , 7 }
x + 3 = -1
x = -1 - 3
x = -4
x + 3 = 1
x = 1 - 3
x = -2
x + 3 = -7
x = -7 - 3
x = -10
x + 3 = 7
x = 7 - 3
x = 4
Vậy x \(\in\) { -4 ; -2 ; -10 ; 4 }