If z and z̄ are roots of a quadratic with real coefficients, then sum z + z̄ equals:
A2 Re(z) (twice real part)
B0
C|z|
DImaginary
Answer & Solution
Correct answer: A. 2 Re(z) (twice real part)
z + z̄ = (a + ib) + (a - ib) = 2a = 2 Re(z). Complex conjugate pairs are roots of real-coefficient polynomials. Sum and product of conjugates are both real.
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