I will assume you mean
y = -√(x-6) and NOT y = -(√x) - 6
start with y = √x
using the following points, sketch the graph.
(0,0), (1,1), (4,2), (9,3), (16,4) ...
(notice I pick numbers that work out nicely)
You will have a "swooping" curve in the first quadrant that rises slowly.
now sketch y = - √x by reflecting your graph in the x-axis, (just flip it downwards)
then move the second graph 6 units to the RIGHT
(move each point 6 units to the right)
domain: any value of x , x ≥ 6
range: any real value of y , y ≤ 0 (all below the x-axis)
To verify, enter
in the "first graph" in
change "Range x-axis from" 6 to 20