JEE Main 2020 — Binomial Theorem Question with Solution
From: JEE Main 2020 (Online) 9th January Evening Slot
Question
If Cr 25Cr and
C0 + 5.C1 + 9.C2 + .... + (101).C25 = 225.k, then k is equal to _____.
C0 + 5.C1 + 9.C2 + .... + (101).C25 = 225.k, then k is equal to _____.
Enter your answer
Show full solutionCorrect answer: 51
Correct answer
51
Step-by-step explanation
S = 1.25C0 + 5.25C1 + 9.25C2 + .... + (101)25C25
S = (101).25C25 + (97).25C24 + .......... + (1).25C0
_________________________________________
2S = 102{25C0 + 25C1 + ......+ 25C25}
S = 51 225 = k.225
k = 51
S = (101).25C25 + (97).25C24 + .......... + (1).25C0
_________________________________________
2S = 102{25C0 + 25C1 + ......+ 25C25}
S = 51 225 = k.225
k = 51
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