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BECE Mathematics 2011 Paper

Question : 25

Total: 40

Given that

a=\binom{5}{2n}

b=\binom{2n-1}{6}

a=b

n

Solution:

Concept:

When two column vectors are equal, their corresponding top and bottom entries must also be equal.

Explanation:

Given

a = \binom{5}{2n}

and

b = \binom{2n-1}{6}

Since

a=b

, equate the top entries:

5 = 2n - 1

Add

1

to both sides:

6 = 2n

Divide both sides by

2

n = 3

Equating the bottom entries gives the same result:

2n = 6

, so

n = 3

Both comparisons confirm the value of

n

Answer:

n = 3

, which is option B.

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