Question

What are the extrema of `f(x) = 8 - 2x` for `x>=6`?

Answer 1

`f(x)` is a line with a negative slope, so on the interval `x>= 6`, the maximum is at `x=6`. There is no minimum because `f(x)` is always decreasing, and the interval given is `[6,oo]`.
graph{-2x+8 [-4.25, 15.75, -7.8, 2.2]}