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Linear Equations — Digital SAT SAT Math revision notes

A 3-page visual revision sheet for Linear Equations, 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 Equations revision notes, page 1 of 3 Page 1 as PDF
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Linear Equations in one look

one unknown or two: isolate, rearrange, and always substitute back

The four forms worth recognising

  • one variable, standard ax + b = 0
  • two variables, standard Ax + By = C
  • slope-intercept y = mx + b
  • point-slope, through (x_1,y_1) y - y_1 = m(x - x_1)

Q. Solve 4(x - 3) + 5x = 2x + 9.

  1. distribute the 4 across the bracket: 4x - 12 + 5x = 2x + 9
  2. collect like terms on the left: 9x - 12 = 2x + 9
  3. move the x terms one way, the numbers the other: 9x - 2x = 9 + 12
  4. 7x = 21, so divide both sides by 7

Answer: x = 3

Slope, three ways to get it

  • from two points m = y_2 - y_1/x_2 - x_1
  • rise over run m = Δ y/Δ x
  • from Ax + By = C m = -A/B,quad b = C/B

how many solutions does ax + b = cx + d have

  • a is not equal to c — exactly one solution: the x terms do not cancel, so x lands on one number
  • a = c but b is not equal to d — no solution: x cancels and leaves a false number statement
  • a = c and b = d — infinitely many solutions: the two sides are literally the same expression

Page 1 of 3. The full sheet, all 3 pages, opens free in the app.

What this Linear Equations sheet covers

Open the full Linear Equations 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 Equations 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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