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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.

Linear Functions revision notes, page 1 of 3 Page 1 as PDF
A 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 function f(x) = mx + b
  • f(a) means put a in place of x
  • slope from two outputs m = f(x_2) - f(x_1)/x_2 - x_1
  • one step along x f(x+1) - f(x) = m
  • n steps along x f(x+n) - f(x) = mn

Q. The function g is defined by g(x) = 1/2x - 4. If g(k) = 6, what is k?

  1. g(k) means substitute k for x: 1/2k - 4 = 6
  2. add 4 to both sides: 1/2k = 10
  3. 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.

What this Linear Functions sheet covers

Open the full Linear Functions sheet →Free, works offline, no account needed. All 3 pages, plus a study plan built around your own exam dates.

How CapCompass uses this sheet

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.

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