19. Let consider the function y = f(x) = x2 -2. a) Show that the points P(1,-1) and O(2,3) are points on the graph of y = f(x) . b) Find the slope of the secant line that passes through the points P and Q. c) Find the equation of the secant line that passes through the points P and 20. Find the equation of the tangent line at the point P(2,-1) to the curve y = f(x) represented graphically bellow. 21. Find the equation of the tangent line at the given number (point). a) y= x' + 2x at x=-1 b) y=1-vx-2 at P(6,-1) 63. Use the function given in the right figure to find each limit. a) lim f(x) b) lim f(x) X-3 c) lim f(x) d) lim f(x) x-+ 2* e) lim f(x) f) lim f(x) x-+0 g) lim f(x) h) lim f (x) 4 -3 x-+2 X-+3 2 64. Use the function given in the right figure to find each limit. a) lim f(x) b) lim f(x) c) lim f(x) d) lim f(x) *+1 e) lim f(x) f) lim f(x) x-+3 g) lim f(x) h) lim f (x) *+-1 X-+3 4 65. Find each limit. If the limit does not exist then explain why. a) lim vx -3 b) lim 14-3' x+3 66. Find each limit. If the limit does not exist then explain why. a) lim vx2 -1 b) lim - 1+2x-2 67. Find each limit. If the limit does not exist then explain why. a) lim vx - 2 b) lim