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complex numbers
Chapter 1 - Complex numbers
Term | Definition |
---|---|
The imaginary unit | i = sqrt(-1) |
"real" numbers definition | non-imaginary numbers |
"imaginary" numbers definition | numbers defined only in terms of i |
complex numbers definition | a number that has real and imaginary parts |
general form of a complex number | z = a + bi |
addition of complex numbers | z1 + z2 = a + bi + c + di = (a+ c) + (b + d)i |
multiplication of complex numbers | z1z2 = (a + bi)(c + di) = ac + (ad + bc)i - bd |
summation of 2 squares formula | a^2 + b^2 = (a + bi)(a - bi) |
i^n function | has period 4, i -> -1 -> -i -> 1 |
the complex conjugate of z | if z = a + bi, z* = z - bi |
complex division | equivilant to realising the denominator, multiply the numerator/denominator by the complex conjugate of the denominator |
solving for z | let z = a + bi, expand as necessary. Form 2 equations from the real and imaginary parts and solve simutaniously |
quadratic in terms of its roots | x^2 -(Alpha + Beta)x + (AlphaBeta) |
sum of the roots of a quadratic | Alpha + Beta = -b/a |
multiplication of the roots of a quadratic | AlphaBeta = c/a |
imaginary roots | complex roots of a polynomial with real co-effecients always come in conjugate pairs |
General roots | Σα = -b/a Σαβ = c/a Σαβγ = -d/a Σαβγδ = e/a etc |