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Problem 4 - Entrance Test

A point P(4, k) lies on the circle with equation (x - 1)^2 + (y + 2)^2 = 34. What are the possible values of k?

Correct: A

Since the point P(4, k) lies on the circle, its coordinates must satisfy the circle's equation. Substitute x = 4 and y = k into the equation: (4 - 1)^2 + (k + 2)^2 = 34 (3)^2 + (k + 2)^2 = 34 9 + (k + 2)^2 = 34 (k + 2)^2 = 34 - 9 (k + 2)^2 = 25 Take the square root of both sides: k + 2 = ±sqrt(25) k + 2 = ±5 Two possible cases: 1) k + 2 = 5 => k = 5 - 2 => k = 3 2) k + 2 = -5 => k = -5 - 2 => k = -7 So, the possible values of k are -7 and 3.