1. Formulas for C ( n,r ) 2. Binominal Coefficient 3. Binomial Theorem 4. Number of Subsets 1
2
Work the route problem covered previously by selecting where in the string of length 7 the 4 E’s will be placed instead of the 3 S’s. Therefore the total number of possible routes is 3 Notice that C(7,4) = C (7,3).
Another notation for C ( n,r ) is. 4 is called a binominal coefficient.
5
Binomial Theorem 6
Expand ( x + y ) 5. 7 (x + y ) 5 = x 5 + 5x 4 y + 10x 3 y x 2 y 3 + 5xy 4 + y 5
A set with n elements has 2 n subsets. 8
A pizza parlor offers a plain cheese pizza to which any number of six possible toppings can be added. How many different pizzas can be ordered? Ordering a pizza requires selecting a subset of the 6 possible toppings. There are 2 6 = 64 different pizzas. 9
C(n,r ) is also denoted by. The formula C(n,r ) = C(n,n - r ) simplifies the computation of C(n,r ) when r is greater than n /2. The binomial theorem states that 10
A set with n elements has 2 n subsets. 11