8.1 	b) plot x^3/3 - 5x,4x-18,-1/4*x-21/4,  where x from -4 to 4
	d) plot 1/(x^2+1),x/2+1,-2x-3/2 where x from -2 to 2


8.2	a) plot x^2-2x,2x-4,  where x from -4 to 4
	c) plot -(2x-1)^3, 24x-13-1/1728, 24x-11+1/1728 where x=-1..1,y=-1..1

8.3	plot 2+1/x,4-x where x=0..4,y=0..4