Algebra Function Basic Flashcards
(251 cards)
In algebra, how is a function defined in simplest terms?
A rule that assigns each input exactly one output.
What is the ‘domain’ of a function f?
All possible input values (x-values) for which f(x) is defined.
What is the ‘codomain’ of a function?
The set in which all outputs of the function are allowed to lie.
What is the ‘range’ (or image) of a function?
All actual output values the function produces from its domain.
What does it mean for a relation to ‘fail the vertical line test’?
At least one vertical line intersects the graph in more than one point, so it is not a function.
Define a ‘one-to-one’ (injective) function.
A function where each output is produced by at most one input (distinct inputs → distinct outputs).
Define an ‘onto’ (surjective) function.
A function whose range equals its entire codomain (every element in the codomain is mapped from some input).
What does ‘bijective’ mean for a function?
It is both injective and surjective, so it has a perfect one-to-one correspondence between domain and codomain.
In function notation, f: A → B, what do A and B represent?
A is the domain, B is the codomain.
What is the difference between ‘range’ and ‘codomain’?
Range is the actual set of outputs. Codomain is the set from which outputs can potentially come.
How do you typically find the domain of a function given by an expression?
Identify values of x that make the expression undefined or invalid (e.g., dividing by zero, negative radicands for even roots), then exclude them.
How do you find the domain of a rational function f(x) = P(x)/Q(x)?
Exclude values for which Q(x) = 0 from the real domain.
What is the domain of f(x) = √(x - 3) in real numbers?
All x ≥ 3.
What is the domain of f(x) = 1/(x + 2) in real numbers?
All real x except x ≠ -2.
If f(x) = √(x + 4) + (1/(x - 2)), how do you determine domain?
First x + 4 ≥ 0 → x ≥ -4, and x - 2 ≠ 0 → x ≠ 2. Combine to get x ≥ -4 but x ≠ 2.
Give an example of a function with domain all real numbers ℝ.
Any polynomial, e.g., f(x) = x² + 1.
How do you typically find the range of a function algebraically?
Solve y = f(x) for x in terms of y, then determine permissible y-values (sometimes more advanced).
What is the range of the function f(x) = x², x ∈ ℝ?
All real y ≥ 0.
What is the range of f(x) = 2x + 3, x ∈ ℝ?
All real numbers (−∞, ∞).
For f(x) = 1/x, x ≠ 0, what is its range in real numbers?
All real y except y ≠ 0.
Define a linear function in one variable.
A function of the form f(x) = mx + b, where m and b are constants.
Define a constant function.
A function where f(x) = c for all x in the domain, c is a constant.
What is a polynomial function?
A function f(x) = aₙxⁿ + … + a₁x + a₀ where coefficients aᵢ are real numbers and exponents are nonnegative integers.
Define a quadratic function.
A polynomial function of degree 2: f(x) = ax² + bx + c, with a ≠ 0.