I have difficulty written sentences. But i know what i am talking about.
I rewrite that sentence to a questions.
Why the steps in Wolfram Alpha could be correct? If yes, how?
Wolfram Alpha suggests using the substitution precisely what is inside the square root. With that, the integrand becomes just . Now, what about dx?
Well, if then u(x- 1)= ux- u= x+ 1 so ux- x= u+ 1, x(u- 1)= u+1, and . From that, .