6 marksThe Binomial Theorem
CAPE Pure Mathematics Unit 2 · May/June 2010 · Paper 2 · Question 4(a)(i)
By expressing ^n\mathrm{C}_r and ^n\mathrm{C}_{r-1} in terms of factorials, prove that ^n\mathrm{C}_r + {}^n\mathrm{C}_{r-1} = {}^{n+1}\mathrm{C}_r.
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