Question 478425
	-0.6x2 + 12x + 11																
a.	Does the graph of this equation open up or down? How did you determine this? (5pts)																
	DOWN - because the coefficient of the highest power term is negative. 																
	How did you determine this? 																
. 																	
B .	Number of ticket sales goes down to zero.																
c.	c. Use the quadratic equation to determine the last day that tickets will be sold. (Note: Write your answer in terms of the number of days after ticket sales begin.)																
	Solve E(x) = 0 for "x>0".																
																	
	E(x) =	-0.2	X^2	+	12	x 	+	11									
																	
	Find the roots of the equation by quadratic formula																
										-b/2a=	30						
	a=	-0.2	b=	12	c=	11											
																	
	b^2-4ac=	144	-	8.8													
	b^2-4ac=	152.8			{{{sqrt(	152.8	)}}}=	12.36									
	{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}																
	{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}																
	x1=(	-12	+	12.36	)/	-0.4											
	x1=	-0.9		- 8/9													
	x2=(	-12	-12.36	) /	-0.4												
	x2= 	60.9		60 8/9													
	Take the positive solution -				The sale goes down to 0 on the 					day	61						
	The x co-ordinate of the parabola is -b/2a						=	30									
	The peak will occur after about 							30	days								
																	
	Plug value of x co-ordinate of vertex in the equation																
	y=	-180	+	360	+	11											
	y=	191															
	191	Tickets will be sold when the sale reaches the peak.															
																	
	The x co-ordinate of the parabola is -b/2a																
	plug the vakue of x in the equation to get the y co-ordinate of the vertex.										Vertex		(  	30	, 	191	)

{{{graph(500,500,-50,200,-10,200,y=-0.2x^2+12x+11)}}}