Are a rational expression and its simplified forms equivalent? provide mathematical examples to support your opinions.

Yes rational expression and its simplified forms are equivalent.

Rational expression are those that contain fractions.

Example: 
25/50 is a rational expression but it is not yet in its simplest form.

25/50 ⇒ 5/10 ⇒ 1/2

1/2 is the simplest form of 25/50.

They are equivalent:

1/2 = 25/50
1*50 = 2*25
50 = 50

or 
1/2 = 0.50
25/50 = 0.50