Answer: k = ±6.
- A k = 3
- B k = ±6
- C k = 9
- D k = ±3
Correct answer: B. k = ±6
Explanation: Equal roots when D = 0: k² - 36 = 0, k² = 36, 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
Read the full Complex Numbers and Quadratic Equations notes →