Question

A member of a book club wishes to purchase two books from a selection of eight book recommended for a certain month. In how many ways can she choose them?Note: Cr=n!n

Answer 1

28

Explanation:

We can calculate the number of different ways by means of the formula of combinations that is the following:

`_nC_r=(n!)/(r!(n-r)!)`

In this case r = 2 and n = 8, we substitute and calculate the quantity in different ways, just like this:

`\begin{gathered} _8C_2=(8!)/(2!(8-2)!)=(8!)/(2!\cdot6!) \\ \\ _8C_2=28 \end{gathered}`

Therefore, the number of ways she can choose is 28