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

ANSWER:

28

STEP-BY-STEP EXPLANATION:

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

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

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

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

Therefore, the number of ways she can choose is 28