Answer: 5/9 < k ≤ 1 or k ≥ 6.
- A k > 6 only
- B 5/9 < k ≤ 1 or k ≥ 6
- C k < 5/9
- D −1 < k < 5/9
Correct answer: B. 5/9 < k ≤ 1 or k ≥ 6
Explanation: Sum < 0 gives k > −1, product > 0 gives k > 5/9, and D ≥ 0 gives (k−1)(k−6) ≥ 0. Combining: 5/9 < k ≤ 1 or k ≥ 6.
A complex number z = a+ib is plotted as a point (or vector from the origin) on the Argand plane, with the real part along the horizontal axis and the imaginary part along the vertical; its modulus |z| is the vector's length, and its argument θ is the angle from the positive real axis.
Concept context
Complex numbers in a+ib form, modulus, argument, polar form, cube roots of unity, and quadratic equations with complex roots
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