When do I use z·z̄ = |z|² in Complex Numbers, and what does it mean?
a complex number times its conjugate is real.
z·z̄ = |z|² — a complex number times its conjugate is real. Use it when: used to rationalise denominators. Always check the condition holds before plugging in numbers.
Key point
z·z̄ = |z|²
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