Exercise · ZW-FUNCTION-004 · ★★☆ Intermediate
Which rule defines a function from ℝ to ℝ?
Choose one option.
Show answer
- A. f(x) = x²
Explanation
f(x) = x² gives exactly one value for each real x. ±√x gives two values, 1/x is not defined at 0 (the given domain is ℝ) and {x, −x} delivers a set of two values, not a value.
Review the concept: Function
A function f from A to B assigns to each element of A exactly one element of B. A is the domain and B the codomain.
\[f:A\to B\]
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