Question 45468
[5+(4/x)]/[5-(4/x^2)]

Notice how you might have posted your problem.

=[(5x+4)/x]/[(5x^2-4)/x^2]
=[(5x+4)/x]*[x^2/(5x^2-4)]
=x(5x+4)/(5x^2-4)

No, you cannot cancel the 5x^2 as they are terms; only
factors may be canceled.

Cheers,
Stan H.