Permutations and Combinations Properties

From Maths Unplugged's Crash Course video on Permutations and Combinations! Question Mode: Flashcards only. Answer mode: Answer with Definition. Good luck!

$$^nC_{n-r}$$

$$^nC_r$$

$$^nC_0$$

$$1$$

$$^nC_n$$

$$1$$

$$^nC_1$$

$$n$$

$\dfrac{^nC_r}{^nC_{r-1}}$ 

$\dfrac{n-r+1}{r}$ 

$$\dfrac{n}{r}\ ^{n-1}C_{r-1}$$

$$^nC_r$$

$$^nC_r + ^nC_{r+1}$$

$$^{n+1}C_{r+1}$$

$$^{n+1}C_{r+1}-^nC_{r+1}$$

$$^nC_r$$

$^nC_x=\ ^nC_y \implies$ 

either $x=y$ or $x+y=n$