Question

Evaluate the expression: 20C4

Answer 1

Answer:

4845

Step-by-step explanation:

Given 20C4 this means  ₂₀C₄

Apply the formula for combinations without repetition

$nCr=\frac{n!}{(n-r)!.r!}$

where

n is the number of things to choose from and r is what you choose from them

Given that ;

n=20

r=4

n-r=20-4=16

Insert values in the equation

$20C4=\frac{20!}{16!*4!} \\\\\\=\frac{16!*17*18*19*20}{16!*4!} \\\\\\=\frac{17*18*19*20}{1*2*3*4} \\\\\\=17*19*15\\\\\\=4845$