Question

Tìm cặp số nguyên x,y biết: (x-2).(y+3)=15

Answer 1

(x - 2)(y + 3) = 15

<=> xy + 3x - 2y - 6 = 15

<=> xy + 3x - 2y = 21

<=> \(\left\{{}\begin{matrix}x=\dfrac{21+2y-3x}{y}\\y=\dfrac{21+2y-3x}{x}\end{matrix}\right.\)

Answer 2

\(\left(x-2\right)\left(y+3\right)=15=3\cdot5=15\cdot1=\left(-3\right)\left(-5\right)=\left(-15\right)\left(-1\right)\)
Ta có bảng:

\(x-2\)	3	5	15	1	-3	-5	-15	-1
\(y+3\)	5	3	1	15	-5	-3	-1	-15
\(x\)	5	7	17	3	-1	-3	-13	1
\(y\)	2	0	-2	12	-8	-6	-4	-19