37. If 4x - 9 = f(x) = x2 - 4x + 7 for x = 0, find lim f(x). 38. If 2x 0 (a) Sketch the graph of this function. (b) Find each of the following limits or explain why it does not exist. (i) lim sgn x (ii) lim sgn x (iii) lim sgn x (iv) lim sgn x 48. Let g(x) = sgn(sin x). (a) Find each of the following limits or explain why it does not exist. (i) lim g(x) (ii) lim g(x) (iii) lim g(x)