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20 12 the last question of quadratic function in Liuzhou mathematics senior high school entrance examination (this question is simplified from the previous questions)
AB is the diameter ≈ ACB = 90, which is obtained from δ AOC δ Cob, OA/AC=OC/OB,

∴OC^2=OA*OB,……①

Let C(0, m) be analyzed by parabola: y =-2 (x-n) 2+2, and y =-2x 2+4nx+2-2n 2 is obtained.

∴m=2-2n^2,……②

Let Y=0 to get (x-n) 2 = 1, x = n 1, ∴ a (n- 1 0), b (n+ 1 0), and substitute them into ①.

M 2 = | 1-n | (1+n), ∴ m2 = (1-n 2), and substitute them into ② respectively.

1-n^2=2-2n^2,

N =+ 1, because of translation to the right, the case of n=- 1 is abandoned, that is, translation to the right 1 unit.

∴m=0, the parabola passes through the origin, and the parabola is y =-2 (x- 1) 2+2.