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Domain Restriction for Inverse
publish date: 2026/05/23 21:36:31.782700 UTC
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Consider the function \( f(x)=x^2 \) defined on the domain \( x \in \mathbb{R} \). Does \( f(x) \) have an inverse function on this domain?
Correct Answer
No, because the function is not one-one (injective) on \(\mathbb{R}\)
Explanation
For a function to have an inverse, it must be bijective (one-one and onto). The function \( f(x) = x^2 \) fails the horizontal line test on \( \mathbb{R} \) because distinct inputs (e.g., \( x=2 \) and \( x=-2 \)) map to the same output (\( 4 \)). Therefore, it is not injective and does not have an inverse unless the domain is restricted (e.g., to \( x \ge 0 \)).
Reference
Introduction to Differential Calculus (Systematic Studies with Engineering Applications for Beginners) - 2012
