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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:

\;a=b

\;\binom{5}{2n}=\binom{2n-1}{6}

The top at the left equals the top at the right and the down at the left equals the down at the right.

Method I

Top at left equals top at the right.

\;5=2n-1

\;5+1=2n

\;6=2n

Divide both sides by 2

\;\;\frac{6}{2}=n

\;n=3

Method II

Down at the left equals down at the right

2n=6

Divide both sides by 2

\;n=\;\frac{6}{2}

\;n=3

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