Tuesday, February 23, 2016

What is the area of the region bounded by the curve y=2x^2+2x, x axis and lines x=1 and x=2?

We'll have to determine the definite integral of the given
function. We'll use Leibniz-Newton formula to calculate the definite
integral:


Int f(x)dx =
F(b)-F(a)


We'll calculate the indefinite integral of
f(x):


Int f(x)dx = Int (2x^2 +
2x)dx


We'll use the property of integral to
be additive:


Int (2x^2 + 2x)dx = Int 2x^2dx + Int
2xdx


Int 2x^2dx = 2*x^3/3 +
C


Int 2xdx = 2*x^2/2 + C


We'll
reduce and we'll get:


Int 2xdx = x^2 +
C


Int (2x^2 + 2x)dx = 2x^3/3 + x^2 +
C


F(2) - F(1) = 2^4/3 + 2^2 - 2/3 -
1^2


F(2) - F(1) = 14/3 +
3


F(2) - F(1) =
23/3


The area bounded by the curve of f(x), x
axis and the lines x=1, x=2  is A=23/3 square
units.

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