Use the Combinations Formula
Use the formula for
$$\mathrm { n } ^ { \mathrm { C } _ { \mathrm { r } } }$$ to evaluate the expression.
-$9 C _ { 5 }$
A) 126
B) 3024
C) 72,576
D) 15,120

Question

Use the Combinations Formula
Use the formula for
 $$\mathrm { n } ^ { \mathrm { C } _ { \mathrm { r } } }$$ to evaluate the expression.
-$9 C _ { 5 }$
A) 126
B) 3024
C) 72,576
D) 15,120

Quizplus · Accepted Answer

The formula for combinations is $ \mathrm { n } ^ { \mathrm { C } _ { \mathrm { r } } } = \frac{n!}{r!(n-r)!} $. For $9 C _ { 5 }$, it is $\frac{9!}{5!(9-5)!} = \frac{9!}{5!4!} = \frac{362,880}{120 \times 24} = 126$.

Use the Combinations Formula Use the Formula For nCr\mathrm { n } ^ { \mathrm { C } _ { \mathrm { r } } }nCr​

Use the Combinations Formula
Use the Formula For $\mathrm { n } ^ { \mathrm { C } _ { \mathrm { r } } }$