f(x) = x²-4x-5, quadratic function,
Domain (the values if x) is all real numbers.
To find range we should draw a graph or to write an equation in vertex form.
f(x) = x²-4x+4-4-5
f(x) = (x-2)²-9
Point (-2,-9) is the vertex of the parabola, and it is a minimum because a parabola has positive sign in front of x², so it is looking up. Minimum value of y =-9
Range(the values of y) is [-9, ∞)
