All 3 Uses

positive
in
The Things They Carried
(Edited)

...you can't change what can't be changed, there it is, there it absolutely and positively and fucking well is.
Chpt 1

positively = with certainty
It was what had brought them to the war in the first place, nothing positive, no dreams of glory or honor, just to avoid the blush of dishonor.
Chpt 1 *

positive = good
"You sure?"
"Positive."
Chpt 15 *

positive = certain

Definitions:

(1) (positive as in: I'm absolutely positive!)
certain (having no doubt; or used for emphasis)
(2) (positive as in: had a positive effect)
good or beneficial
(3) (positive as in: positive feedback from my boss)
approval or agreement
(4) (positive as in: a positive attitude)
optimistic (expecting or focusing on good things); or agreeable
(5) (positive as in: The test came back positive.)
found a condition or substance to be present
indicating the presence of something being tested for -- especially a disease, condition, or substance
(6) (positive as in: a positive number)
greater than zero (of a number)
(7) (meaning too rare to warrant focus)
See a comprehensive dictionary for less common meanings of positive including some in the fields of electricity, physics, chemistry, medicine, philosophy, and grammar. Note that most all senses of positive indicate that something is good or present.