Question

Evaluate. 9!/7! A.) 63 B.) 72 C.) 81

Answer 1

ANSWER

B.) 72

EXPLANATION

Recall the expansion for the factorial notation:

$n! = n \times (n - 1) \times (n - 2) \times ...3 \times 2 \times 1$

We want to simplify

$\frac{9!}{7!}$

Let us expand the numerator up to 7! while maintaining the denominator.

$\implies \: \frac{9 \times 8 \times 7!}{7!}$

When we cancel out the common factors,we obtain:

$\implies \: \frac{9 \times 8 \times 1}{1}$

This simplifies to

$\implies \: \frac{72}{1} = 72$

The correct answer is B.