Which of the following shows the prime factorization of 72 using exponential notation?

A. [tex]\(2^3 \cdot 3^2\)[/tex]

B. [tex]\(2^2 \cdot 3^2\)[/tex]

C. [tex]\(8 \cdot 9\)[/tex]

D. [tex]\(2 \cdot 6^2\)[/tex]



Answer :

To solve this problem, we need to find the prime factorization of the number 72 and then express it in exponential notation. Let’s break down the problem step-by-step:

1. Identify the number:
We need the prime factors of 72.

2. Divide by the smallest prime number:
Begin by dividing 72 by the smallest prime, which is 2:
- [tex]\( 72 \div 2 = 36 \)[/tex]
- [tex]\( 36 \div 2 = 18 \)[/tex]
- [tex]\( 18 \div 2 = 9 \)[/tex]

Now, we have divided by 2 three times, which means [tex]\( 2^3 \)[/tex].

3. Continue with the next smallest prime:
After obtaining 9, we continue the factorization with the next smallest prime, which is 3:
- [tex]\( 9 \div 3 = 3 \)[/tex]
- [tex]\( 3 \div 3 = 1 \)[/tex]

We have divided by 3 twice, which means [tex]\( 3^2 \)[/tex].

4. Combine the prime factors:
The prime factorization of 72 is [tex]\( 2^3 \cdot 3^2 \)[/tex].

5. Match with given options:
Comparing our result with the given options:
- [tex]\( 8 \cdot 9 \)[/tex]:
[tex]\[ 8 = 2^3 \text{ and } 9 = 3^2 \][/tex]
This option is breakdown into prime factors, matching [tex]\(2^3 \cdot 3^2\)[/tex].

- [tex]\( 2 \cdot 6^2 \)[/tex]:
[tex]\[ 6 = 2 \cdot 3 \text{ so } 6^2 = (2 \cdot 3)^2 = 2^2 \cdot 3^2 \][/tex]
This breaks down to [tex]\( 2 \cdot 2^2 \cdot 3^2 = 2^3 \cdot 3^2 \)[/tex].

- [tex]\( 2^3 \cdot 3^2 \)[/tex]:
This directly matches our breakdown of prime factorization [tex]\(2^3 \cdot 3^2\)[/tex].

- [tex]\( 2^2 \cdot 3^2 \)[/tex]:
This does not match our factorization since it is [tex]\( 2^3 \cdot 3^2 \)[/tex], not [tex]\( 2^2 \cdot 3^2 \)[/tex].

Thus, the correct option that shows the prime factorization of 72 using exponential notation is:
[tex]\[ \boxed{2^3 \cdot 3^2} \][/tex]