📈 Functions: Domain, Range & Transformations
FunctionsCommon questions
How to find the domain of a function?
Identify restrictions: denominators ≠ 0, even roots ≥ 0, log arguments > 0, inverse trig arguments in valid range. Domain = all x satisfying all restrictions simultaneously.
What are function transformations?
Shifts (f(x)+k up, f(x-h) right), reflections (−f(x) over x-axis, f(−x) over y-axis), stretches (af(x) vertical, f(bx) horizontal). These compose in order.
How to determine if a function is one-to-one?
Use the horizontal line test: if any horizontal line intersects the graph at most once, it is one-to-one. Algebraically: f(a)=f(b) implies a=b.
What is the range of common JEE functions?
sin/cos: [-1,1], tan: (-∞,∞), eˣ: (0,∞), ln(x): (-∞,∞), x²: [0,∞). For composite functions, apply range restrictions in order.
Why are functions important for JEE?
Functions underpin calculus, coordinate geometry, and algebra. JEE tests domain/range, composition, inverse functions, and functional equations — typically 2-3 questions.