Question

Tìm số tự nhiên x, y biết:

(x - 3)(y + 5) = 9

Answer 1

\(\left(x-3\right)\left(y+5\right)=9\)

Do \(y\in N\Rightarrow\) \(\left(y+5\right)\)\(\ge5\)

\(x\in N\Rightarrow x-3\ge-3\)

\(\Rightarrow\left\{x-3;y+5\right\}=\left\{1;9\right\}\\ \Rightarrow\left\{x;y\right\}=\left\{4;4\right\}\)