Exercise · ZW-LAW-OF-QUADRATIC-RECIPROCITY-003 · ★★☆ Intermediate

Compute \(\left(\frac{3}{5}\right)\left(\frac{5}{3}\right)\).

Choose one option.

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  • A. \(1\)

Explanation

Since not both primes are congruent to 3 modulo 4, the product equals 1, not -1.

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Review the concept: Law of quadratic reciprocity

The law of quadratic reciprocity relates the Legendre symbols \(\left(\frac{p}{q}\right)\) and \(\left(\frac{q}{p}\right)\) for distinct odd primes \(p\) and \(q\).

\[\left(\frac{p}{q}\right)\left(\frac{q}{p}\right)=(-1)^{\frac{(p-1)(q-1)}{4}}\]

More practice problems: law of quadratic reciprocity

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