Exercise · ZW-INVERSE-ELEMENT-001 · ★☆☆ Basic

What is the inverse of 5 in (ℤ, +)?

Choose one option.

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  • D. −5

Explanation

The inverse of 5 in (ℤ, +) is −5, because 5 + (−5) = 0, which is the identity. 1/5 would be the multiplicative inverse and is not an integer.

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Review the concept: Inverse element

Given \(a\in G\), an element \(b\in G\) is an inverse of \(a\) if operating in both orders gives the neutral element.

\[a\ast a^{-1}=a^{-1}\ast a=e\]

More practice problems: inverse element

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