Question

prove that n(n-1)(n-2)....(n-r+1)=n!/(n-r)!

Answer 1

This may help you. .

Answer 2

Answer:

$\frac{x}{y}\sqrt[n]{x} \sqrt[n]{x} \sqrt{x} \\ \\ x^{2} \sqrt{x} \sqrt{x} \alpha \sqrt{x} \sqrt{x} \sqrt{x} \sqrt{x} \sqrt{x} \sqrt{x} \sqrt{x} \sqrt{x} \left[\begin{array}{ccc}1&2&3\\4&5&6\\7&8&9\end{array}\right]$÷⇔∉∫∝∝∝∞㏒㏒㏒㏒㏒㏒㏒㏒㏒║║║║║║║║║║Δ,,

Explanation: