申論題

5. A lattice path from (x₀, y₀) to in the ay plane is defined as a sequence of points (x₀, y₀), (x₁,y₁), , such that each and each,    ± 1,i =1,2, n - 1. How many lattices paths are there from (0,1) to (10,3)? How many of them do not touch or cross the t axis?