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As shown in the figure, it is a part of the graph of quadratic function & nbsp; y = AX2 + BX + C (a ≠ 0). The following propositions are given: ① a + B + C = 0; ② b > 2A; ③ two of AX2 + BX + C = 0 are - 3 and 1 respectively; ④ a-2b + C > 0. The correct proposition is () A. ①②B. ②③C. ①③D. ①②③④
When ∵ x = 1, y = 0, ∵ a + B + C = 0, so ① is correct; when ∵ x = - B2A = - 1, ∵ B = 2A, so ② is wrong; when ∵ point (1,0) is symmetric with respect to the line x = - 1, the coordinates of the intersection of the parabola and the X axis are (- 3,0) and (1,0), the two coordinates of ∵ AX2 + BX + C = 0 are - 3 and 1 respectively, so ③ is correct; when the intersection of the parabola and the Y axis is below the X axis, ∵ C < 0, and a + B +C = 0, B = 2A, ∫ C = - 3a, ∫ a-2b + C = - 3b, ∫ B ＞ 0, ∫ 3b ＜ 0, so ④ is wrong
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