Question

Bài 6:

a) x+5 chia hết cho x+3

b) 2x-1 chia hết cho x+2

Answer 1

a/ \(x+5⋮x+3\Leftrightarrow x+3+2⋮x+3\)

Vì \(x+3⋮x+3\) nên để \(x+5⋮x+3\) thì \(2⋮x+3\), tức là \(\left(x+3\right)\in U\left(2\right)\Rightarrow\left(x+3\right)\in\left\{-2;-1;1;2\right\}\Rightarrow x\in\left\{-5;-4;-2;-1\right\}\)

KL: ....................

b/ \(2x-1⋮x+2\Leftrightarrow2\left(x+2\right)-5⋮x+2\)

Vì \(2\left(x+2\right)⋮x+2\) nên để \(2x-1⋮x+2\) thì \(5⋮\left(x+2\right)\), tức là \(\left(x+2\right)\in U\left(5\right)\Rightarrow\left(x+2\right)\in\left\{-5;-1;1;5\right\}\Leftrightarrow x\in\left\{-7;-3;-1;3\right\}\)

KL: .................