Can someone give me a proper answer please!! I really need help. I just need the highlighted ones.

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value

that is the sum

step-by-step explanation:

there are no other answers without knowing the variables values