A²-b²=(a+b)*(a-b). and. (a+b)²= (a+b)*(a+b).
As we can see the common division here is (a+b), so the answer is A) (a+b)

Set of numbers is the largest positive integer that divides all the numbers in the set without leaving a remainder. It is also known as the highest common factor (HCF).

To find the GCD of a set of numbers, you can use various methods such as prime factorization, Euclidean algorithm, or using a calculator.

For example, let's find the GCD of the numbers 12, 18, and 24.

1. Prime Factorization Method:
- Write the prime factorization of each number:
12 = 2^2 * 3
18 = 2 * 3^2
24 = 2^3 * 3
- Identify the common prime factors: 2 and 3.
- Multiply these common prime factors together: 2 * 3 = 6.
- Therefore, the GCD of 12, 18, and 24 is 6.

2. Euclidean Algorithm:
- Start by dividing the first two numbers: 18 ÷ 12 = 1 remainder 6.
- Then divide the divisor (12) by the remainder (6): 12 ÷ 6 = 2 remainder 0.
- Since the remainder is 0, the last divisor (6) is the GCD.
- Therefore, the GCD of 12, 18, and 24 is 6.

3. Using a Calculator:
- Many calculators have a GCD function that can find the GCD of a set of numbers.
- Input the numbers 12, 18, and 24 into the calculator and use the GCD function.
- The calculator will display the GCD, which should be 6.

All three methods give the same result, which is the GCD of the set of numbers.