यदि \(A=\{1,2,3,4,5\}\), तो \(A\times A\) में (a) और (b) परस्पर अभाज्य होने वाले युग्मों की संख्या कितनी है?
If \(A=\{1,2,3,4,5\}\), how many pairs in \(A\times A\) have (a) and (b) relatively prime?
Explanation opens after your attempt
C. (19)
Concept
The non-coprime pairs are ((2,2),(2,4),(3,3),(4,2),(4,4),(5,5)). Thus (25-6=19) pairs are relatively prime.
Why this answer is correct
The correct answer is C. (19). The non-coprime pairs are ((2,2),(2,4),(3,3),(4,2),(4,4),(5,5)). Thus (25-6=19) pairs are relatively prime.
Exam Tip
अभाज्य न होने वाले युग्म ((2,2),(2,4),(3,3),(4,2),(4,4),(5,5)) हैं। कुल (25-6=19) युग्म परस्पर अभाज्य हैं।
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