Tuesday, December 20, 2011

Find the area bounded by y=8-x^2 and y=x^2.

First, we'll have to identify the limits of integration.
For this rason, we'll determine the intercepting points of the
graphs.


Since y = x^2 and y = 8-x^2, we'll
get:


x^2 = 8-x^2


We'll move
all terms to one side:


x^2 - 8 + x^2 =
0


2x^2 - 8 = 0


We'll divide by
2:


x^2 - 4 = 0


x^2 =
4


x1 = 2 and x2 = -2


Over the
interval [-2 ; 2] the graph 8-x^2 >= x^2


The area of
the region is the definite integral of the function 8 - x^2 - x^2, for x = -2 to x =
2.


A = Int (8 - x^2 - x^2)dx


A
= Int (8 - 2x^2)dx


A = Int 8dx -  Int
2x^2dx


A = 8x - 2x^3/3, for x = -2 to x =
2


A = 8(2 + 2) - (2/3)(8 +
8)


A = 32 - 32/3


A =
(96-32)/3


A = 64/3 square
units.


The area is A =  64/3 square
units.

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