MHB What Does It Mean for Expressions to Be Non-Integral and Non-Rational?

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Expressions are considered non-integral when they do not consistently yield integer values, as seen in the example $\frac{4y}{x}$, which fails to be integral in x unless x is specifically 1 or a common factor. Non-rational expressions, like $3x\sqrt{y}z^3$, do not always produce rational values; in this case, y must be a perfect square of a rational number for the expression to be rational. The distinction between integral and rational is crucial in understanding the behavior of algebraic expressions. Non-integral and non-rational expressions can lead to undefined or non-standard results in mathematical contexts. Understanding these concepts is essential for accurate mathematical analysis and problem-solving.
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can you explain what it means when they are not "Integral" and not "Rational"?

$\frac{4y}{x} = 4yx^{-1 }$ is not integral in x
$3x\sqrt{y}z^3$ not rational in y
 
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Drain Brain said:
can you explain what it means when they are not "Integral" and not "Rational"?

$\frac{4y}{x} = 4yx^{-1 }$ is not integral in x
$3x\sqrt{y}z^3$ not rational in y

To be integral, your expression needs to always give an integer value. If x is anything but 1 or a common factor of the top, then your first expression will not be integral.

To be rational, your expression needs to always give a rational (fractional) value. If y is anything but a perfect square of a rational number, then the second expression will not be rational.
 
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