यदि \(A=\{1,2,3,4,5\}\) और \(B=\{3,6,9,12\}\) हैं, तो \(A\times B\) में कितने युग्म ((a,b)) ऐसे हैं जिनमें (b=3a) है?
If \(A=\{1,2,3,4,5\}\) and \(B=\{3,6,9,12\}\), how many pairs ((a,b)) in \(A\times B\) satisfy (b=3a)?
Explanation opens after your attempt
C. (4)
Concept
For (a=1,2,3,4), we get (b=3,6,9,12), but for (a=5), \(15\notin B\). Hence there are (4) pairs.
Why this answer is correct
The correct answer is C. (4). For (a=1,2,3,4), we get (b=3,6,9,12), but for (a=5), \(15\notin B\). Hence there are (4) pairs.
Exam Tip
(a=1,2,3,4) पर (b=3,6,9,12) मिलता है, पर (a=5) पर \(15\notin B\)। इसलिए (4) युग्म हैं।
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