Find the equation of the set of all points the sum of whose distance from the points `(3,0)a n d(9,0)` is `12.`

Explanation

To find the equation of the set of all points such that the sum of their distances from the points (3, 0) and (9, 0) is 12, we can follow these steps:

### Step 1: Define the points and the variable point
Let the variable point be \( P(x, y) \). The fixed points are \( A(3, 0) \) and \( B(9, 0) \).

### Step 2: Write the distance formula
The distance from point \( P(x, y) \) to point \( A(3, 0) \) is given by:
\[
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