The functions f and g are defined as follows: f:xx-2x, xER, g:x2x+3, XER. (i) Find the set of values of x for which f(x) > 15. (ii) Find the range of f and state, with a reason, whether f has an inverse. [3] [4] (iii) Show that the equation gf(x) = 0 has no real solutions. [3] (iv) Sketch, in a single diagram, the graphs of y = g(x) and y = g(x), making clear the relationship between the graphs. [2]