- Let $n\geq t\geq 0$. Show that $$\sum_{j=t}^{n}\binom{j}{t}=\binom{n+1}{t+1}$$ I am stuck on this question. The fact thats it is multivariable is confusing me.
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Thomas Andrews
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Student54125
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Don't worry about $t$. Just show it is true with $n=t$ and then show if true for $n$ then it is true for $n+1$. – Thomas Andrews Nov 07 '16 at 17:57
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You’ll find several different proofs at the earlier question, including algebraic and combinatorial proofs and a proof by induction. – Brian M. Scott Nov 07 '16 at 18:06