Question

Tìm số nguyên a biết 17 chia hết cho 2a + 3.

Answer 1

Do \(17⋮2a+3\) mà \(a\in Z\) nên \(2a+3\inƯ\left(7\right)=\left\{-1,1,7,-7\right\}\)

\(\Rightarrow2a\in\left\{-4,-2,4,-10\right\}\)

\(\Leftrightarrow a\in\left\{-2,-1,2,-5\right\}\)

Answer 2

Sửa lại xíu ạ : Khi đó \(2a+3\in\left\{1,-1,17,-17\right\}\)

\(\Leftrightarrow a\in\left\{-1,-2,7,-10\right\}\)

Answer 3

\(17⋮2a+3\\ \Rightarrow2a+3\inƯ\left(17\right)\\ \Rightarrow2a+3\in\left\{1;17;-1;-17\right\}\\ \Rightarrow a\in\left\{-1;-2;-10\right\}\)

Vậy \(a\in\left\{-1;-2;-10\right\}\)