5. Domain restriction
푓 is NOT a function on
Functions & Graphs 5
푓: 푥 ⟼
1
푥 − 2
풟 = ℝ
풟 = 푥 푥 ∈ ℝ ∧ 푥 ≠ 2
푓 IS a function on
6. Domain by context
Functions & Graphs 6
푣 푡 =
100
푡
Average velocity
푣 푡 is mathematically a function on 풟 = 푡 푡 ∈ ℝ ∧ 푡 ≠ 0
푣 푡 is by context a function on 풟 = 푡 푡 ∈ ℝ ∧ 푡 > 0
Photo: Wikipedia.org
18. Inverse function
푓−1 Is the inverse function of 푓 if:
푓 ∘ 푓−1 푥 = 푓−1 ∘ 푓 푥 = 푥
퐷푓−1 = ℛ푓
푅푓−1 = 퐷푓
Only one-to-one functions are invertible !
Functions & Graphs 18
19. END
Disclaimer
This document is meant to be apprehended through professional teacher mediation (‘live in class’)
together with a mathematics text book, preferably on IB level.
Functions & Graphs 19