To determine the primitive of te given function, we'll
calculate the indefinite integral of the function.
Int (ln
x)^2dx/x^2
We'll replace ln x by
t.
ln x = t
x =
e^t
We'll differentiate both
sides:
dx/x = dt
Int (ln
x)^2dx/x^2 = Int t^2*e^(-t)dt
We'll solve the integral in
variable t using parts.
Int udv = u*v - Int
vdu
Let u = t^2 => du =
2tdt
dv = e^(-t) dt => v =
-e^(-t)
Int t^2*e^(-t)dt = -t^2*e^(-t) + 2Int
t*e^(-t)dt
We'll integrate again Int t*e^(-t)dt by
parts:
u = t => du =
dt
dv = e^(-t) dt => v =
-e^(-t)
Int t*e^(-t)dt = -t*e^(-t) + Int e^(-t)
dt
Int t*e^(-t)dt = -t*e^(-t) - e^(-t) +
C
Int t^2*e^(-t)dt = -t^2*e^(-t) + 2*[-t*e^(-t) - e^(-t)] +
C
Int t^2*e^(-t)dt = -t^2*e^(-t) - 2t*e^(-t) - 2e^(-t) +
C
Int t^2*e^(-t)dt = -t^2/e^t - 2t/e^t - 2/e^t +
C
Int t^2*e^(-t)dt = -(t^2 + 2t + 2)/e^t +
C
Int (ln x)^2dx/x^2 = -[(ln x)^2 + 2ln x + 2)/x +
C
The antiderivative of the given function is
F(x) = -[(ln x)^2 + 2ln x + 2)/x + C.
No comments:
Post a Comment