Friday, June 19, 2015

Integrate [((log(5) x)^2 + sqrt 2*(log(5) x) + 9)/x] with respect to x.

We have to integrate: [((log(5) x)^2 + sqrt 2*(log(5) x) +
9)/x] with respect to x.


use the relation log(a)x = ln x/ln
a


[((log(5) x)^2 + sqrt 2*(log(5) x) +
9)/x]


=> [((ln x/ln 5)^2 + sqrt 2*(ln x/ln 5) +
9)/x]


=> (1/ln 5)(ln x)^2/x + (sqrt 2/ln 5)(ln x)/x
+ 9/x


Int[(1/ln 5)(ln x)^2/x + (sqrt 2/ln 5)(ln x)/x +
9/x]dx


To find Int[(ln x)^2/x
dx]


let y = ln x


dy/dx = 1/x
or dy = dx/x


=> Int[y^2
dy]


=> y^3/3


substitute
y = ln x


=> (ln
x)^3/3


Similarly lnt[ln x/x dx] = (ln
x)^2/2


=> (1/ln 5)(ln x)^3/3 + (sqrt 2/ln 5)(ln
x)^2/2 + 9 ln x + C


The required integral is
(1/ln 5)(ln x)^3/3 + (sqrt 2/ln 5)(ln x)^2/2 + 9 ln x +
C

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