Answer: x = (-b ± √D) / 2a.
- A x = (-b ± √D) / 2a
- B x = (b ± √D) / 2a
- C x = (-b ± D) / 2a
- D x = (-b ± √D) / a
Correct answer: A. x = (-b ± √D) / 2a
Explanation: Quadratic formula: x = (-b ± sqrt(b² - 4ac)) / 2a. Works for all quadratic equations.
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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