Functions — Class 11 Maharashtra HSC Mathematics revision notes
A 5-page visual revision sheet for Functions, written for Class 11 Maharashtra HSC Mathematics. 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.
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Functions in one look
one rule, one output for every input: domain, range and the shapes that follow
Function, Domain, Co-domain, Range
a function f:Ato B sends each x in A to exactly one y in B, y=f(x)
A is the domain of f, B the co-domain, y is the image of x
range = f(A): every y actually hit, always a subset of the co-domain
vertical line test: no vertical line may cut the graph of a function twice
horizontal line test: no horizontal line may cut the graph twice, so f is one-one
One-one and onto
one-one (injective): different elements of A have different images, f(a)=f(b)⇒ a=b
onto (surjective): every y in B is the image of some x in A, so f(A)=B
range of f = f(A) subset co-domain of f, with equality exactly when f is onto
The four combinations
one-one, not onto: every arrow lands on a different target, but some targets are unused
one-one and onto: a bijection: every target hit exactly once
onto, not one-one: every target is hit, but some target is hit twice
neither one-one nor onto: some target unused, another hit more than once
Worked: evaluating a function
Q. if f(x)=2x^2-3x+4, find f(7) and f(-2t)
f(7)=2(7)^2-3(7)+4=2(49)-21+4
=98-21+4=81
f(-2t)=2(-2t)^2-3(-2t)+4=2(4t^2)+6t+4
Answer: f(7)=81, f(-2t)=8t^2+6t+4
Six ways to represent a function
verbal: a sentence describing the rule, e.g. output exceeds twice the input by 1
arrow/Venn diagram: domain and range as two ovals joined by arrows
ordered pairs: pairs like (2,5),(3,7),(4,9),(5,11); domain is the 1st entries, range the 2nd
rule/formula: y=f(x)=2x+1, with a stated domain
tabular: a two-row table of x and y values
graphical: domain is the graph's projection on the X-axis, range its projection on the Y-axis
Page 1 of 5. The full sheet, all 5 pages, opens free in the app.
What this Functions sheet covers
Function, Domain, Co-domain, Range
One-one and onto
The four combinations
one-one, not onto
onto, not one-one
neither one-one nor onto
Worked: evaluating a function
Six ways to represent a function
Shapes of the basic functions
Domain and range, basic functions
Worked: domain and range of a square-root function
These notes are not a standalone PDF. CapCompass plans Mathematics chapter by chapter against your real exam dates and free hours, and when the plan reaches 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.