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 (a+b=6) या (a=b) 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 (a+b=6) or (a=b)?
Explanation opens after your attempt
B. (9)
Concept
There are (5) pairs with (a+b=6) and (5) with (a=b), but ((3,3)) is counted twice. Hence (5+5-1=9).
Why this answer is correct
The correct answer is B. (9). There are (5) pairs with (a+b=6) and (5) with (a=b), but ((3,3)) is counted twice. Hence (5+5-1=9).
Exam Tip
(a+b=6) वाले (5) और (a=b) वाले (5) युग्म हैं, पर ((3,3)) दो बार गिना गया। इसलिए (5+5-1=9)।
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