Question

Find the indefinite integral. (Remember to use absolute values where appropriate. Use C for the constant of integration.) dx x(ln x2)5

Answer 1

I'm assuming the integral is

$\displaystyle \int \frac{dx}{x (\ln(x^2))^5}$

We have

$\ln(x^2) = 2 \ln|x| \implies (\ln(x^2))^5 = 32 (\ln|x|)^5$

Then substituting $y=\ln|x|$ and $dy=\frac{dx}x$, the integral transforms and reduces to

$\displaystyle \int \frac{dx}{x(\ln(x^2))^5} = \frac1{32} \int \frac{dy}{y^5} \\\\ ~~~~~~~~ = \frac1{32} \left(-\frac1{4y^4}\right) + C \\\\ ~~~~~~~~ = -\frac1{128(\ln|x|)^4} + C$

which we can rewrite as

$128 (\ln|x|)^4 = 8\cdot2^4(\ln|x|)^4 = 8 (2\ln|x|)^4 = 8 (\ln(x^2))^4$

and so

$\displaystyle \int \frac{dx}{x (\ln(x^2))^5} = \boxed{-\frac1{8(\ln(x^2))^4} + C}$