Write the following sets in the roster form :
the set if signs of four fundamental operations of arithmetic.

Answer

To write the set of signs of the four fundamental operations of arithmetic in roster form, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Four Fundamental Operations**: The four fundamental operations of arithmetic are addition, subtraction, multiplication, and division. Their respective signs are:
- Addition: +
- Subtraction: -
- Multiplication: ×
- Division: ÷

2. **List the Signs**: Now, we will list these signs in a set. In set notation, we use curly braces `{}` to denote a set.

3. **Write the Set in Roster Form**: The roster form of the set will include all the signs we identified. Therefore, we can write the set as:
\[ A = \{ +, -, \times, \div \} \]

### Final Answer:
The set of signs of the four fundamental operations of arithmetic in roster form is:
\[ A = \{ +, -, \times, \div \} \]

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