is the point and is the point . The perpendicular bisector of crosses the -axis at . What is ?

Answer and explanation

Correct answer: E.

  1. Step 1: The midpoint of is and the gradient of is .
  2. Step 2: The perpendicular gradient is , so the bisector is .
  3. Step 3: At : .
Answer
.
Why not the others: is the -coordinate of the midpoint, where rather than ; using the gradient instead of would give , which is not an integer; and do not satisfy .

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