11.3	solve y''-3y'+2y=0

11.4	c) (c*e^x+d-x-x^2/2)''-(c*e^x+d-x-x^2/2)'-x
	f) (sin x -1 + c*e^(-sin x))'+(sin x -1 + c*e^(-sin x))*cos x - (sin 2x)/2

11.5	i) solve y'=2sqrt(y)
	y=(x+1)^2, y=(x+2)^2, y=(x-3)^2 where y=-10..10

11.6	b) solve (x+1)*y'+(2-y)=0
	c) solve y*(y+1)*y'=1/(x-1)
	g) solve(1+x^2)dy-sqrt(1-y^2)dx=0
	h) solve sqrt(1-x^2)dy-sqrt(1-y^2)dx=0

11.7	b) solve y'=e^(x+y), y(0) = 0
	d) solve y*x*y'+(x^2-1)=0, y(1)=0

11.9	solve dy/dt = k*y, y(0)=10^7
	plot 10^7*e^(2*x), 10^7*e^(-1*x)		
	
11.12	solve dy/dx = 1/250*y(1000-y) with y(0)=2
	plot 1000*e^(4x)/(e^(4x)+499) where x = 0..10
	solve 1000*e^(4x)/(e^(4x)+499) = 500

11.13	:(

11.14	a) solve y'-3y/x-x=0
	b) solve y'-y=x^2
	d) solve y'-y*cos(x)=x^2*e^(sin x)
	f) solve xy'-y+x^2=0
	g) solve y'-y=x-1
	h) solve xe^xy'+ye^x=1
	q) solve xy'+y/(x+1)=x, y(1)=0