The equation AX2 + 2x + 1 = 0 has at least one negative real root if and only if () A. 0 < a < 1b. 0 < a ≤ 1 or a < 0C. 0 ≤ a ≤ 1D. A ≤ 1

The equation AX2 + 2x + 1 = 0 has at least one negative real root if and only if () A. 0 < a < 1b. 0 < a ≤ 1 or a < 0C. 0 ≤ a ≤ 1D. A ≤ 1

When a = 0, we get x = - 12. When a ≠ 0, it is obvious that the equation has no root equal to zero. If the equation has two real roots with different signs, we get a < 0 according to the relationship between the root and the coefficient; if the equation has two negative real roots, we get a < 0 according to the relationship between the root and the coefficient; 1A ＞ 0 − 2A ＜ 0 △ = 4 − 4A ≥ 0  0 ＜ a ≤ 1. To sum up, if the equation has at least one negative real root, then a ≤ 1. The equation AX2 + 2x + 1 = 0 of X has at least one negative real root if and only if a ≤ 1