Moving only south and east along the line segments, how many paths are there from A to B?

MIRB16
Mar 8, 2018

#1**+1 **

**Moving only south and east along the line segments, how many paths are there from A to B?**

\(\begin{array}{|rcll|} \hline && {^{12}}C_3- {^5}C_1 {^6}C_1- {^6}C_1 {^5}C_1 \\ &=& {^{12}}C_3-2\cdot {^5}C_1{^6}C_1 \\ &=& 220-2\cdot 30 \\ &=& 220-60 \\ &=& 160 \\ \hline \end{array}\)

heureka
Mar 8, 2018