\(\dfrac{15}{n-3}\in Z\)
\(\Rightarrow n-3\inƯ\left(15\right)\)
\(\Rightarrow n-3\in\left\{1;-1;3;-3;5;-5;15;-15\right\}\)
`=> n-3=1=>n=4`
`=> n-3=-1=>n=2`
`=>n-3=3=>n=6`
`=>n-3=-3=> n=0`
`=> n-3=5=>n=8`
`=>n-3=-5=>n=-2`
`=>n-3=15=>n=18`
`=>n-3=-15=>n=-12`
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