\(\sum_{r=0}^{n}r{}^{n}C_r x^r\) किस derivative identity से जुड़ा है?
Which derivative identity is connected with \(\sum_{r=0}^{n}r{}^{n}C_r x^r\)?
Explanation opens after your attempt
Correct Answer
A. (nx(1+x)^{n-1})
Concept
Differentiate ((1+x)^n) and multiply by (x) to obtain this sum. In exams think of the derivative method when a factor (r) appears.
Why this answer is correct
The correct answer is A. (nx(1+x)^{n-1}). Differentiate ((1+x)^n) and multiply by (x) to obtain this sum. In exams think of the derivative method when a factor (r) appears.
Exam Tip
((1+x)^n) को differentiate करके (x) से multiply करने पर यह sum मिलता है। परीक्षा में (r) factor दिखे तो derivative method सोचें।
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