A linear approximate
- divide and conquer
- change complex into simple things
- HOW: approximation
which one is simpler: parabola or a line?
Can we study a line with infinite ends? — Line segment (between two points) — Domain and Range
In reality, we don’t care about a thing if it does not change at all. We pay attention only if it changes.
Why? we can predict tomorrow based on one thing’s changing rules.
Change: I Ching
Change: y2-y1 & x2-x1
Rate of Change: The slope of the secant line
Average? Remember this line between (x1, y1) and (x2, y2) is approximating to the function we are actually interested.
Imagine: line segments become infinite short
Log of the trip
The steep part of the curve tells you:
The flat part of the curve tells you:
Increasing, decreasing, extrema
What is the opposite of “Relative“?
Concavity, inflection point
Increasing, Decreasing, Concavity up / down
