Title: Microeconomics / Q2 / mod1: production part2

Q: Concavity
A: for any two points x and y in its domain and any α ∈ [0, 1], the following inequality holds: f(αx + (1 - α)y) ≥ αf(x) + (1 - α)f(y). the line segment joining any two points on the graph of the function lies below the graph itself.
f''(x) ≤ 0
For example:

Q: Rational preferrence relation
A: satisfies "completeness" and "transitivity