Nonlinear Functions — Digital SAT SAT Math revision notes
A 3-page visual revision sheet for Nonlinear 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.
Nonlinear Functions in one look
parabolas, exponentials, and what a shift does to an equation
Nonlinear means the rate of change itself changes
a linear function adds the same amount every step. A quadratic adds a growing amount, and an exponential multiplies by the same factor every step
that one distinction answers most of the modelling questions: added each time is linear, multiplied each time is exponential
a quadratic drawn on axes is a parabola, and every parabola has a vertex (its highest or lowest point) and an axis of symmetry through it
the graph of a function and its equation carry the same information. The question decides which of the two is quicker to read
One quadratic, three forms
standard form, and c is the y-intercepty=ax^2+bx+c
vertex form, vertex at (h,k)y=a(x-h)^2+k
factored form, x-intercepts at p and qy=a(x-p)(x-q)
axis of symmetry, which is also the x of the vertexx=-b/2a
sum of the two roots, with no factorising at allp+q=-b/a
Worked: intercepts and vertex
Q. h(x)=x^2-8x+12. What is the sum of the x-intercepts of y=h(x), and where is the vertex?
x-intercepts are the x values with h(x)=0: x^2-8x+12=0
factorise: (x-2)(x-6)=0, so x=2 and x=6
their sum is 8, which is also -b/a=8, so the factorising was optional for this part
the vertex sits on the axis of symmetry, midway between the roots: x=2+6/2=4
substitute back for the height: h(4)=16-32+12=-4
Answer: the intercepts sum to 8, and the vertex is (4,-4)
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What this Nonlinear Functions sheet covers
Nonlinear means the rate of change itself changes
One quadratic, three forms
standard form, and c is the y-intercept
vertex form, vertex at (h,k)
factored form, x-intercepts at p and q
axis of symmetry, which is also the x of the vertex
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 Nonlinear 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.