The unit of density is:
Kilograms per cubic centimeter.
<h2>Step-by-step explanation:</h2>We know that the density of a substance is defined as the ratio of the mass of a substance to it's volume.
i.e.
Now, we know that the standard unit of the mass of a substance is: Kilograms(kg)
and the standard unit for a volume is: cubic centimeters(cm³)
Hence, we will get the unit for density as:
Kilograms per cubic centimeter
<u>Directrix:</u>
If the vertex of the parabola is at (0, 0) and the focus is (0, -4) <em>which is 4 units down</em><em> </em>then the directrix will be the line 4 units UP.
Answer: y = 4
<u>Equation of parabola:</u>
; where p is the distance from the vertex to the focus.
As stated above, the focus is 4 units down, so p = -4
Answer: