Practice Function in Math
Use these practice problems to test your method after reviewing the concept explanation and worked examples.
Quick Recap
A function is a rule that assigns to each input in the domain exactly one output in the codomain — every input maps to precisely one output, never two.
A machine: put something in, get exactly one thing out. Same input always gives same output.
Example 1
easyDetermine whether the relation \{(1, 3), (2, 5), (3, 7), (4, 9)\} is a function.
Example 2
mediumDoes the equation x^2 + y^2 = 25 define y as a function of x?
Example 3
easyIs the relation \{(2, 4), (3, 6), (2, 8)\} a function? Explain.
Example 4
hardA graph passes through the points (1, 2), (2, 5), (3, 5), and (1, 7). Does this graph represent a function? Explain using the vertical line test.
Example 5
mediumGiven f(x) = 2x^2 - 3x + 1, find f(4) and determine if g = \{(1,2), (3,4), (1,5)\} is a function.