JEE Main 2020 — Binomial Theorem Question with Solution
From: JEE Main 2020 (Online) 6th September Evening Slot
Question
If the constant term in the binomial expansion
of
is 405, then |k| equals :
is 405, then |k| equals :
Choose an option
Show full solutionCorrect option: A
Correct answer
A3
Step-by-step explanation
rth term of the expansion,
Tr+1 = 10Cr
= 10Cr.
= 10Cr.
If it is constant term then
= 0
r = 2
T3 = 10C2.(-k)2 = 405
k2 = = 9
k = 3
|k| = 3
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