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Suppose the normals at three different points on the parabola y2 = 4x pass through the point (h, 0). Show that h > 2 |
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Answer» Let t1, t2 and t3 be the parameters of the feet of the normals drawn from (h, 0). Hence, t1, t2 and t3 are the roots of the cubic equation t3 + (2 - h)t = 0. That is, t1, t2 and t3 are the roots of t(t2 + 2 - h) = 0 Since the equation has three roots, h must be greater than 2. |
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