Section 7.2A Domain and Range

Domain The domain of a function f is the set of all inputs If the problem is a table or a set of ordered pairs the domain is the first coordinate (usually x) If the problem is a graph the domain is the set of all points on the horizontal line. If the problem is an equation the domain is the set all the input numbers. If the problem is a word problem the domain is the set of all input numbers that make sense.

Range The range of a function f is the set of all outputs If the problem is a table or a set of ordered pairs the domain is the second coordinate (usually y) If the problem is a graph the range is the set of all points on the vertical line. If the problem is an equation the range is the set all the output numbers. If the problem is a word problem the range is the set of all output numbers that make sense.

DOMAIN and RANGE TABLE / ORDERED PAIRS GRAPH EQUATION WORD PROBLEMS FUNCTION If the first item does not repeat Passes the VLT Must test 1-1 FUNCTION If the first and second item does not repeat Passes the VLT and HLT DOMAIN All first items All items on the horizontal line All items that go into the equation All items that are allowed into the eq. RANGE All second items All items on the vertical line All items that come out of the equation All items that can come out of the eq.

Ways to write the answers If you have a values here and there you will use the braces {} a list all the valid answers in increasing order. If you have values that are connected, usually in a graph form you will use the brackets [], parentheses (), or a mixture of the two, to group all answers together. Bracket means endpoint is included Parentheses means endpoint is not included Infinite will always use a parentheses