Câu hỏi của ๛๖ۣۜMĭη²ƙ⁸࿐

Question

Tìm x Thuộc Z

x² + 2x + 9 chia hết cho x + 2

Can you tell me about your lover ?

shitbo · Accepted Answer

$x^2+2x+9⋮x+2$

$\Leftrightarrow x\left(x+2\right)+9⋮x+2$

Dễ thấy $x\left(x+2\right)⋮x+2$ nên $9⋮x+2$

$\Rightarrow x+2\in\left\{1;9;-1;-9;3;-3\right\}$

$\Rightarrow x\in\left\{-1;7;-3;-11;1;-5\right\}$

Câu trả lời:

$x^2+2x+9⋮x+2$

$\Leftrightarrow x\left(x+2\right)+9⋮x+2$

Dễ thấy $x\left(x+2\right)⋮x+2$ nên $9⋮x+2$

$\Rightarrow x+2\in\left\{1;9;-1;-9;3;-3\right\}$

$\Rightarrow x\in\left\{-1;7;-3;-11;1;-5\right\}$

x+1	-1	-5	1	5
x	-2	-6	0	4