Evaluate the following expressions. a. 9!/8! b. 7!/5! c. 21!/19! d. 8!/4!

asked Mar 25, 2020 146k views

1 vote

Evaluate the following expressions.
a. 9!/8!
b. 7!/5!
c. 21!/19!
d. 8!/4!

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3 votes

Answer:

Remember,
$n!=1*2*3*\cdots*n$ , then

(9!)/(8!)=(1*2*3*4*5*6*7*8*9)/(1*2*3*4*5*6*7*8)=9

(7!)/(5!)=(1*2*3*4*5*6*7)/(1*2*3*4*5)=6*7=42

$(21!)/(19!)=(1*2*\cdots*19*20*21)/(1*2*\cdots*19)=20*21=420$

(8!)/(4!)=(1*2*3*4*5*6*7*8)/(1*2*3*4)=5*6*7*8=1680

Ziftech answered Mar 31, 2020

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