यदि \(A=\{1,2,3,4\}\) और \(B=\{0,1,2,3,4,5\}\) हैं, तो \(A\times B\) में कितने युग्म ((a,b)) ऐसे हैं जिनमें \(b\equiv a^2 \pmod{5}\) है?
If \(A=\{1,2,3,4\}\) and \(B=\{0,1,2,3,4,5\}\), how many pairs ((a,b)) in \(A\times B\) satisfy \(b\equiv a^2 \pmod{5}\)?
Explanation opens after your attempt
A. (4)
Concept
The residues of \(a^2\) are (1,4,4,1), and each such residue has one value in (B). Therefore there are (4) pairs.
Why this answer is correct
The correct answer is A. (4). The residues of \(a^2\) are (1,4,4,1), and each such residue has one value in (B). Therefore there are (4) pairs.
Exam Tip
\(a^2\) के अवशेष (1,4,4,1) हैं और (B) में हर ऐसे अवशेष का एक-एक मान है। इसलिए कुल (4) युग्म हैं।
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