If the distance between the points `P(a ,2,1)a n d\ Q(1,-1,1)` is 5 units find the value of `adot`

Explanation

To find the value of \( a \) such that the distance between the points \( P(a, 2, 1) \) and \( Q(1, -1, 1) \) is 5 units, we can follow these steps:

### Step 1: Write the distance formula
The distance \( d \) between two points \( P(x_1, y_1, z_1) \) and \( Q(x_2, y_2, z_2) \) in three-dimensional space is given by:
\[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2 + (z_2 - z_1)^2} \]

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