integration by substitution, parens. or absolute valu bars?

[mike09]

Hi, I'm doing integration by substitution using u....I'm noticing that some of the answers show brackets and others show parenthesis when I'm taking the antiderivative of ln.

For example, parenthesis were involved in answers such as
1/2ln(.3x^2-.4x+2) + c

ln(1+e^x) + c

wheras absolute value bars were used in answers such as

1/6ln|3x-1| + c

-1/5ln|1-x^5| + c

why do some answers use parenthesis and others use absolute value bars? Thanks in advance

[maggiemagnet]

I'm pretty sure that they're all supposed to be absolute values, but people lots of time forget and use parentheses.