यदि \(A=\{1,2,3,4,5\}\) और \(B=\{1,2,3,4,5\}\) हैं, तो \(A\times B\) में कितने युग्म ((a,b)) ऐसे हैं जिनमें (\gcd(a,b)=1) और (a+b) सम है?
If \(A=\{1,2,3,4,5\}\) and \(B=\{1,2,3,4,5\}\), how many pairs ((a,b)) in \(A\times B\) satisfy (\gcd(a,b)=1) and (a+b) even?
Explanation opens after your attempt
B. (7)
Concept
The components must have the same parity and also (\gcd(a,b)=1), giving (7) pairs. Check \(\gcd\) carefully among same-parity pairs.
Why this answer is correct
The correct answer is B. (7). The components must have the same parity and also (\gcd(a,b)=1), giving (7) pairs. Check \(\gcd\) carefully among same-parity pairs.
Exam Tip
दोनों अवयवों की समता समान होनी चाहिए और (\gcd(a,b)=1) भी चाहिए, ऐसे (7) युग्म हैं। सम-सम युग्मों में \(\gcd\) जल्दी जाँचें।
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