Question
Download Solution PDF\(\rm ^nC_{r-3}+2\times (^nC_{r-4})+{^nC_{r-5}}=\)
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFसंकल्पना:
\(\rm ^nC_r+{^nC_{r-1}}= {^{(n+1)}C_{r}}\)
गणना:
दिया गया है: \(\rm ^nC_{r-3}+2\times (^nC_{r-4})+{^nC_{r-5}}\)
= \(\rm ^nC_{r-3}+ (^nC_{r-4})+ (^nC_{r-4})+{^nC_{r-5}}\)
= \(\rm ^{(n+1)}C_{r-3}+ ^{(n+1)}C_{r-4}\) (∵ \(\rm ^nC_r+{^nC_{r-1}}= {^{(n+1)}C_{r}}\))
= \(\rm ^{(n+2)}C_{r- 3}\)
अतः विकल्प (1) सही है।
Last updated on May 30, 2025
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