SOLUTION: What is the solution of the system of inequalities? y&#8805; x^2+2x+2 y< -x^2-4x-2 Thank You!

Algebra ->  Inequalities -> SOLUTION: What is the solution of the system of inequalities? y&#8805; x^2+2x+2 y< -x^2-4x-2 Thank You!      Log On


   



Question 695832: What is the solution of the system of inequalities?
y≥ x^2+2x+2
y< -x^2-4x-2

Thank You!

Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
First let's look at the graph of the two parabolas:
graph%28500%2C+500%2C+-5%2C+5%2C+-5%2C+5%2C+x%5E2%2B2x%2B2%2C+-x%5E2-4x-2%29
The red one is y+=+x%5E2%2B2x%2B2 and the green one is y+=+-x%5E2-4x-2. The solution to y+%3E=+x%5E2%2B2x%2B2 would be the red parabola and all the area above/inside the bowl. The solution to y+%3C+-x%5E2-4x-2 would be all the area below/inside the green parabola. (Not the green parabola itself because that is where y equals -x%5E2-4x-2 and the inequality does not include "or equal to".)

So the solution to the system is where these two areas overlap each other: The enclosed area between the two parabolas. To express this solution we must first find the two points where the parabolas intersect. Setting
x%5E2%2B2x%2B2+=+-x%5E2-4x-2
and solving for x we should be able to find the points of intersection. Subtracting the entire right side we get:
2x%5E2%2B6x%2B4+=+0
Factor out the GCF of 2:
2%28x%5E2%2B3x%2B2%29+=+0
Factoring the trinomial:
2%28x%2B1%29%28x%2B2%29+=+0
From the Zero Product Property:
x + 1 = 0 or x + 2 = 0
Solving:
x = -1 or x = -2

Using these x values and either equation for the parabola we can find that the y values for each x are 1 and 2, respectively. So the points of intersection are:
(-1, 1) and (-2, 2)
So the x values of the solution are between -1 and -2, inclusive:
-2+%3C+x+%3C+-1
and the y values of the solution are:
x%5E2%2B2x%2B2+%3C=+y+%3C+-x%5E2-4x-2