Question

Tìm x , y để:

\(\overline{31xy}\) \(⋮\) 2 ; 3 và 5

Answer 1

mik viết nhầm

\(\overline{31xy}\) \(⋮\)2;5 \(\Rightarrow\)y \(\in\)\(\left\{0\right\}\)

nếu y = 0 ta có : \(\overline{31x0}\)\(⋮\) 3

\(\Rightarrow\) ( 3 + 1 +x + 0 ) \(⋮\) 3

\(\Rightarrow\) (4 + x )\(⋮\) 3

\(\Rightarrow\) x \(\in\)\(\left\{2;5;8\right\}\)

\(\Rightarrow\)\(\overline{31xy}\) = 3120 ; 3150 ; 3180

Answer 2

Để \(\overline{31xy}\) \(_⋮\)2,5 => y \(\in\) \(\in\)

Nếu y = 0 ta có : \(\overline{31x0}\)\(⋮\)3

=> ( 3 + 1 + x + 0 ) \(⋮\)3

=> 4 + x \(⋮\)3

=> x \(\in\) \(\left\{2,5,8\right\}\)

\(_{\Rightarrow}\)\(\overline{31xy}\) = 3120 ;3150 ; 3180