The simplified expression is
and the restriction is 
<h3>How to simplify the expression?</h3>
The expression is given as:

Express x^2 - y^2 as (x + y)(x - y) and factorize other expressions

Rewrite the expression as products

Cancel out the common factors

Express 4x^2 - y^2 as (2x - y)(2x + y)

Cancel out the common factors

Take the LCM

Hence, the simplified expression is
and the restriction is 
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