Is this relation a function? Justify your answer

D

Step-by-step explanation:

To see if a set order of points is a function, you have to do the vertical line test. If there are two points on the same x-axis, like (2,3) and (2,6), then it isn't a function. Although, if there are two points on the same y-axis, like (2,5) and (4,5), then yes, it is a function.

-hope it helps

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.

the rocket cannot penetrate the ground, in a contextual sense, therefore the roots of this equation should be the domain of this function. i'll let you find the roots of this quadratic equation (hint: use the quadratic formula:  

1- c

2-a

step-by-step explanation:

mark brainliest!