Final answer:
The speed of an electron for the given kinetic energies of 750 eV and 3.2 keV should be calculated using the relativistic energy equation, not the classical kinetic energy formula.
Step-by-step explanation:
The speed of an electron with a given kinetic energy can be found using the classical formula for kinetic energy KE = 1/2 mv^2, where m is the mass of the electron and v is its velocity. However, for kinetic energies of 750 eV (electron-volts) and 3.2 keV (kilo-electron-volts), this approach is insufficient as these energies are in the range where relativistic effects become significant. Instead, we would use the relativistic energy equation E = √(p^2c^2 + m^2c^4), where p is the momentum of the electron and c is the speed of light. However, the data provided in the references doesn't directly show the method to calculate the speed of an electron from its kinetic energy, especially considering the relativistic context.