If f(x) = x2 – 1 and g(x) = 2x – 3, what is the domain

Begin by finding the lowest point the quadratic equation can be, the vertex; 

x²-1= is just a translation down of the graph x²

vertex; (0, -1) and since the graph of x² would extend to infinity beyond that point, we can say {x| x≥0} for domain and {y| y≥-1}. 

For the linear equation, it is possible to have all x and y values, therefore range and domain belong to all real numbers. 

Hope I helped :)