Type 2 Improper Integral $\lim_{t \to 1^-} \int^t_0 \frac{1}{\sqrt{|x-1|}} \: dx$

58 Views Asked by At

I have the type 2 improper integral $\lim_{t \to 1^-} \int^t_0 \dfrac{1}{\sqrt{|x-1|}} \: dx$.

My calculations are as follows:

$\lim_{t \to 1^-} \int^t_0 \dfrac{1}{\sqrt{1-x}} \: dx$

Let $u = 1 - x$.

$\implies du = -dx$

Upper limit of integration becomes $u = 1 - t$

Lower limit of integration becomes $u = 1$

$\lim_{t \to 1^-} \int^{1 - t}_1 \dfrac{-1}{\sqrt{u}} \: du$ = $\lim_{t \to 1^-} \left( \dfrac{-2}{\sqrt{u}} \right)^{1 - t}_1$

When I changed the limits of integration due to substitution, did I also have to change the limit value?

$= \lim_{t \to 1^-} \left( \dfrac{-2}{\sqrt{1-t}} + 2\right)$

$= -\infty + 2 $

Therefore, this improper integral is divergent.

I would greatly appreciate it if people could please take the time to review my calculations and check if they're correct. I would also appreciate a response with regards to my question about changing the limit value when I changed the limits of integration.