\(\hept{\begin{cases}x:17\left(dư9\right)\\x:19\left(dư13\right)\end{cases}}\Rightarrow\hept{\begin{cases}17-9:x\\19-13:x\end{cases}\Rightarrow\hept{\begin{cases}12⋮x\\6⋮x\end{cases}}\Rightarrow x\inƯC\left(12;6\right)}\)
\(12=2^2.3\)
\(6=2.3\)
\(ƯCLN\left(12;6\right)=2.3=6\)
Vì x<500
nên x={6;12;18;24....;485;490;490}
cho mk xl , số cuối 495 nha !