The two focuses of hyperbola x2a2 − y2b2 = 1 (a > 0, b > 0) are F1 and F2. If P is the upper point and | Pf1 | = 2 | PF2 |, the value range of hyperbolic eccentricity is () A. (1,3)B. (1,3]C. (3,+∞)D. [3,+∞]

The two focuses of hyperbola x2a2 − y2b2 = 1 (a > 0, b > 0) are F1 and F2. If P is the upper point and | Pf1 | = 2 | PF2 |, the value range of hyperbolic eccentricity is () A. (1,3)B. (1,3]C. (3,+∞)D. [3,+∞]

Let | Pf1 | = x, | PF2 | = y, then x = 2yx − y = 2A, the solution is x = 4A, y = 2A, ∵ in △ pf1f2, x + Y > 2c, that is, 4A + 2A > 2c, 4a-2a < 2c, ∵ 1 < CA < 3, and because when three points and one line, 4A + 2A = 2c, the range of centrifugation is (1, 3), so B