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Glossary Math & Statistics

Complex number

A complex number has a real part and an imaginary part, written a + bi, where i is defined by i² = −1.

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In more detail

Its size is |a + bi| = √(a² + b²), so |3 + 4i| = 5. Complex numbers give every quadratic an answer and describe oscillations such as alternating current.

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See also

  • Glossary Quadratic formula
    The quadratic formula gives the solutions of `ax² + bx + c = 0`: `x = (−b ± √(b² − 4ac)) / 2a`.
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