Stepping into math: Open-sourcing our step-by-step solver

Re:Stepping into math: Open-sourcing our step-by-step solver by gizmo686 on Thursday January 19, 2017 @07:47PM (#13440868)

So, your proposed solution to integral(ln(x)) involves first noticing that d/dx (1/x) = ln(x), then proceeding to use v=1/x to integrate by parts?

I think I am misunderstanding something, because as far as I can tell, integration by parts where one of the parts is 1 is literally useless.

[ Parent | on HN ]

Re:Stepping into math: Open-sourcing our step-by-step solver by yequalsx on Thursday January 19, 2017 @08:00PM (#13440932)

u = ln(x) and dv = 1

du = 1/x and v = x

integral ln(x) = x ln(x) - integral 1/x times x

integral ln(x) = x ln(x) - x + C

I could give integral arctan(x) but with the advent of computer algebra systems I'm mostly interested in them knowing the basic examples and to not burden them on a test with something more complicated.

EDIT: The derivative of 1/x is not ln(x) as you stated. You got it backwards and my guess is that is the source of your confusion.

[ Parent | on HN ]