The domain of the function are all values that you can input, in the graphic, they are all values in the x-axis where the function is defined.
The domain for this kind of function is all real numbers, any real number you imput in the function will generate a valid output.
x∈R.
The range of the variable id determined by all output values, i.e. the values shown in the y-axis. In this case as you see, the function decreases until point (-1,-5), then it stats increasing again towards +∞
There are no outputs defined for this varieble below y=-5 so the range of the variable is all real numbers equal or greater than -5
y≥-5
y∈R