A technician is analyzing an electrical circuit where the impedance is represented by the complex number ${}15 - 8i$ ohms. According to the standard definition of a complex number in the form $a + bi$, which value is the imaginary part?

A telecommunications specialist is analyzing a signal's phase, which is represented by the complex number ${}24 - i$. According to the standard form $a + bi$, the numerical value of the imaginary part of this signal is ____.

An HVAC technician is using a diagnostic tool to measure the electrical load of a system. The tool displays the circuit's impedance as the expression ${}22 - 9i$ ohms. Match each part of this measurement to its correct mathematical designation based on the standard form $a + bi$.

HVAC Vibration Analysis Log

An avionics technician is programming a navigation system using the mathematical expression ${}14 - 9i$ (in the standard form $a + bi$). The imaginary part of this expression is the real number $-9$.