Question

[Lê Hoàng Khánh]

8. Tìm x, y ϵ Z.

\(y=\dfrac{4x-8}{2x+5}\)

Answer 1

[Nguyễn Việt Lâm]

\(y=\dfrac{2\left(2x+5\right)-18}{2x+5}=2-\dfrac{18}{2x+5}\)

\(y\in Z\Rightarrow\dfrac{18}{2x+5}\in Z\Rightarrow2x+5=Ư\left(18\right)\)

Mà 2x+5 luôn lẻ nên ta có: \(2x+5=\left\{-9;-3;-1;1;3;9\right\}\)

2x+5	-9	-3	-1	1	3	9
x	-7	-4	-3	-2	-1	2
y	4	8	20	-16	-4	0

Answer 2

[ILoveMath]