What is int_1^oo 1/(1+x )-1/xdx?

1 Answer
Jul 16, 2016

= ln (1/2)

Explanation:

int_1^oo 1/(1+x )-1/xdx

= [ ln(1+x )- ln x ]_1^oo

= [ ln((1+x )/x) ]_1^oo

= [ ln((1/x+1 )/1) ]_1^oo

= lim_{x to oo} ln((1/x+1 )/1) - ln((1/1+1 )/1)

= lim_{x to oo} ln((1/x+1 )/1) - ln((1/1+1 )/1)

= ln 1 - ln 2 = ln (1/2)