यदि ( \frac{n!}{(n-2)!}=9n ), तो (n) का धनात्मक मान क्या है?
If ( \frac{n!}{(n-2)!}=9n ), what is the positive value of (n)?
Explanation opens after your attempt
B. (10)
Concept
The left side is (n(n-1)), so (n(n-1)=9n). Since (n>0), (n-1=9) and (n=10).
Why this answer is correct
The correct answer is B. (10). The left side is (n(n-1)), so (n(n-1)=9n). Since (n>0), (n-1=9) and (n=10).
Exam Tip
बायां पक्ष (n(n-1)) है, इसलिए (n(n-1)=9n)। (n>0) होने से (n-1=9) और (n=10)।
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