(^{n}C_2=\frac{n(n-1)}{2}) किस सूत्र से सरल होकर आता है?
From which formula does (^{n}C_2=\frac{n(n-1)}{2}) simplify?
Explanation opens after your attempt
Correct Answer
D. (^{n}C_2=\frac{n!}{2!(n-2)!})
Concept
In the combination formula after cancelling ((n-2)!) the term (n(n-1)) remains. In exams remember \(^{n}C_2\) as the pair-making formula.
Why this answer is correct
The correct answer is D. (^{n}C_2=\frac{n!}{2!(n-2)!}). In the combination formula after cancelling ((n-2)!) the term (n(n-1)) remains. In exams remember \(^{n}C_2\) as the pair-making formula.
Exam Tip
Combination formula में ((n-2)!) कटने पर (n(n-1)) बचता है। परीक्षा में \(^{n}C_2\) को जोड़े बनाने का सूत्र मानें।
Login to save your score, XP, coins and progress.