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JEE MATHEMATICS MCQ: PERMUTATIONS

1 Easy

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Application +4 | -1

If

{\;^{18}}{C_{15}} + 2\left( {{\;^{18}}{C_{16}}} \right) + {\;^{17}}{C_{16}} + 1 = {\;^n}{C_3}

, then

n

is equal to

View answer and explanation

Correct option: B

20

Option B (20) is correct because simplifying the given expression using combination identities leads to

^{20}C_3

, thus n = 20.

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