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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 28 Page 704

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

28

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=6. Let's substitute these values into the formula.

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

n= 8, r= 6

_8 C_6 = 8!/( 8- 6)! 6!

Subtract term

_8 C_6 = 8!/2! 6!

Write as a product

_8 C_6 = 8* 7* 6!/2! 6!

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

_8 C_6 = 8* 7/2!

2!=2

_8 C_6 = 8* 7/2

Multiply

_8 C_6 = 56/2

Calculate quotient

_8 C_6 = 28

Subchapter links

Communicate Your Answer p.699

Monitoring Progress p.700-703

Exercises p.704-706