You can put this solution on YOUR website! f(x) =y=(5x-1)/(x^2-16)
Normally in Domain problems we seek when denominator =0
this becomes easier to see if we factor denominator
y= (5x-1) / ( x+4) (x-4)
x+4 =0, x=-4
x-4 =0, x=4
Therefore domain is all Real numbers except x= +4, or =-4