Find the smallest set `A` such that `Auu{1,2}={1,2,3,5,9}dot`

Explanation

To find the smallest set \( A \) such that \( A \cup \{1, 2\} = \{1, 2, 3, 5, 9\} \), we can follow these steps:

### Step 1: Understand the union operation
The union of two sets includes all the elements from both sets. Therefore, for \( A \cup \{1, 2\} \) to equal \( \{1, 2, 3, 5, 9\} \), all elements from the right side must be present in the union.

**Hint:** Remember that the union operation combines all unique elements from both sets.

### Step 2: Identify the elements in the result set
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