Solution of Cubic and Quartic Equations

In this paper a, b are complex numbers. The following propositions are true: (1) a · a = a2. (2) a · a · a = a3. (3) a · a · a · a = a4. (4) (a− b) = (a2 − 2 · a · b) + b2. (5) (a− b) = ((a3 − 3 · a2 · b) + 3 · b2 · a)− b3. (6) (a− b) = (((a4 − 4 · a3 · b) + 6 · a2 · b2)− 4 · b3 · a) + b4. Let n be a natural number and let r be a real number. We introduce r1/n as a synonym of n √ r. Let n be a non zero natural number and let z be a complex number. The functor n √ z yields a complex number and is defined by: (Def. 1) n √ z = |z|1/n · (cos( z n ) + sin( Arg z n ) · i).