generals336

2021-01-10

Prove that for

Ayesha Gomez

Skilled2021-01-11Added 104 answers

Prove that for

$n\ge 2,2\cdot \left(\begin{array}{c}n\\ 2\end{array}\right)+\left(\begin{array}{c}n\\ 1\end{array}\right)={n}^{2}$

Step 1. Definitions

Definition combination

$nCr=\left(\begin{array}{c}n\\ r\end{array}\right)=\frac{n!}{r!(n-r)!}$

with$n!=n\times (n-1)\times \cdots \times 2\times 1$ .

Pascals

Step 1. Definitions

Definition combination

with

Pascals