Answer: -9.
- A -6
- B 6
- C 9
- D -9
Correct answer: D. -9
Explanation: Let t = |x| (t ≥ 0). The equation becomes t²−t−6 = 0, factoring as (t−3)(t+2) = 0. Only t = 3 is non-negative, so |x| = 3, giving x = 3 or x = −3. Product of all real roots = 3 × (−3) = −9.
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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