What does the line y=k-1/4a represent in y=a(x-h)^2+k, the standard form of equation for a parabola?

The line y=k-1/4a represent in y=a(x-h)^2+k is:

                                   Directrix.              

Directrix of a parabola--

A directrix is a line which is perpendicular to the axis of symmetry of a parabola and it does not touch the parabola.

Also, for the standard equation of the parabola i.e.

The equation of directrix of a parabola is given by:

im not sure

step-by-step explanation:

answer: 4  

the square root of 16 is 4. it is a very simple mathematic concept. a square root when a number multiplied by itself will result in a number. here, the number 16 comes when 4 is multiplied by 4. hence the square root of 16 is 4. you can always figure out a square root by the inverse operation of squaring.