Linear Functions — Digital SAT SAT Math revision notes
A 3-page visual revision sheet for Linear Functions, written for Digital SAT SAT Math. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDFA preview of page 1 — all 3 pages open full size in the app.
Linear Functions in one look
one rate, one starting value, and a graph that never changes its mind
Function notation, stripped down
the shape of every linear functionf(x) = mx + b
f(a) meansput a in place of x
slope from two outputsm = f(x_2) - f(x_1)/x_2 - x_1
one step along xf(x+1) - f(x) = m
n steps along xf(x+n) - f(x) = mn
Q. The function g is defined by g(x) = 1/2x - 4. If g(k) = 6, what is k?
g(k) means substitute k for x: 1/2k - 4 = 6
add 4 to both sides: 1/2k = 10
multiply both sides by 2
Answer: k = 20
Nonzero slope vs zero slope
m is not 0
the output changes at a steady rate
the graph crosses the horizontal axis exactly once
there is exactly one x with f(x) = 0
m = 0
f(x) = b for every input, a constant function
the graph is a flat horizontal line
no x makes f(x) = 0 unless b is already 0
Page 1 of 3. The full sheet, all 3 pages, opens free in the app.
These notes are not a standalone PDF. CapCompass plans SAT Math chapter by chapter against your real exam dates and free hours, and when the plan reaches Linear Functions the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.