Saturday, April 4, 2015

What is the definite integral of x^2*e^x between the limits x = 0 and x = 1?

We'll integrate by parts the function,
twice.


We'll use the
formula:


Int udv = u*v-Int
vdu


We'll put u = x^2 => du =
2x


We'll put dv = e^x => v =
e^x


We'll apply the
formula:


Int x^2*e^x dx = x^2*e^x - Int 2x*e^x
dx


We'll repeat the procedure again for the term Int
2x*e^xdx:


We'll put u = 2x => du =
2


We'll put dv = e^x => v =
e^x


We'll apply the
formula:


Int 2x*e^xdx = 2x*e^x - 2Int e^x
dx


Int 2x*e^xdx = 2x*e^x -
2e^x


The integral of the given function
is:


Int x^2*e^x dx = x^2*e^x - 2x*e^x +
2e^x


We'll apply Leibniz
Newton:


F(1) = e - 2e + 2e =
e


F(0) = 2


Int x^2*e^x dx =
F(1) - F(0) = e - 2


The definite integral of
the given function is: Int x^2*e^x dx = e - 2.

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