Answer: b² - 4ac.
- A b - 4ac
- B b² + 4ac
- C b² - 4ac
- D b² - 2ac
Correct answer: C. b² - 4ac
Explanation: Discriminant D = b² - 4ac. It determines the nature of roots.
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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