Graphing a function
f(x)= -sqrt 1-x
or negative square root one minus x

First notice that f(x) is negative, so entire graph will be below x-axis.
Next find domain by setting what is inside sqrt greater than 0.
You can't take sqrt of neg number.

Finally plot some points, start at x = 1, y=0.
Then try x = 0, y = -1.
x = -3, y = -2.
Connect the points, done.