what is the rational algebraic expressions and not rational algebraic expressions

Answer:
In mathematics, an algebraic expression is an expression built up from integer constants, variables, and the algebraic operations (addition, subtraction, multiplication, division and exponentiation by an exponent that is a rational number).[1] For example, 3x2 − 2xy + c is an algebraic expression. Since taking the square root is the same as raising to the power
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{\displaystyle {\sqrt {\frac {1-x^{2}}{1+x^{2}}}}} {\sqrt {\frac {1-x^{2}}{1+x^{2}}}}