Tìm a,b ∈ Z biết : ( a - 1 ) ( b + 3 ) = -7

Đáp án:

`( a - 1 ). ( b + 3 ) = -7` 

Do `a, b ∈ ZZ`

`-> a - 1; b + 3 ∈ ZZ`

`→ a - 1; b + 3 ∈ Ư_{(-7)} = {1;-1;7;-7}`

Lập bảng giá trị

                \begin{array}{|c|c|c|}\hline \text{a - 1}&\text{1}&\text{-1}&\text{7}&\text{-7}\\\hline \text{b + 3}&\text{-7}&\text{7}&\text{-1}&\text{1}\\\hline \text{a}&\text{2}&\text{0}&\text{8}&\text{-6}\\\hline \text{b}&\text{-10}&\text{4}&\text{-4}&\text{-2}\\\hline\end{array}

Vậy `(a;b) = (2;-10);(0;4);(8;-4);(-6;-2)`

$#dariana$