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Big Ideas Math Geometry, 2014

BI

Big Ideas Math Geometry, 2014 View details

5. Permutations and Combinations

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Exercise 26 Page 704

Recall the formula for a combination, _n C_r = n!/(n-r)! r!.

56

Practice makes perfect

To evaluate the given combination, we will use the corresponding formula. _n C_r = n!/(n-r)! r! We are given that n=8 and r=5. Let's substitute these values into the formula.

_n C_r = n!/(n-r)! r!

n= 8, r= 5

_8 C_5 = 8!/( 8- 5)! 5!

Subtract term

_8 C_5 = 8!/3! 5!

Write as a product

_8 C_5 = 8* 7* 6* 5!/3! 5!

a/b=.a /5!./.b /5!.

_8 C_5 = 8* 7* 6/3!

Write as a product

_8 C_5 = 8* 7* 6/3* 2* 1

Multiply

_8 C_5 = 8* 7* 6/6

a/b=.a /6./.b /6.

_8 C_5 = 8* 7/1

a/1=a

_8 C_5 = 8* 7

Multiply

_8 C_5 = 56

Subchapter links

Communicate Your Answer p.699

Monitoring Progress p.700-703

Exercises p.704-706