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