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This lesson explores the concept of functions, including determining if a relation is a function, using the vertical line test, finding the domain and range, and evaluating functions. Examples and practice problems are provided.
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Functions Warm-Up: Given f(x) = 2x – 3 what is f(-2)? What about 3f(-2)? TS: Making decisions after reflection and review
Objectives • To determine if a relation is a function. • To use the vertical line test to decide whether an equation defines a function. • To find the domain and range of a function. • To use function notation to evaluate functions.
Functions A function is a machine.
Functions You put something in.
Functions Information is processed.
Functions You get something out.
Functions PEOPLE Michael Tony Yvonne Justin Dylan Megan Elizabeth Emily BLOOD TYPE A B AB O • A function is a relation in which every element in the domain is paired with exactly one element in the range.
Function? Function Function Not a Function
Function? • {(1, 2), (3, 4), (5, 6), (7, 8)} Function • {(1, 2), (3, 2), (5, 6), (7, 6)} Function • {(1, 2), (1, 3), (5, 6), (5, 7)} Not a Function
Vertical Line Test • If a vertical line can intersect a graph in more than one point, then the graph is not a function.
Function? Function Not a Function Domain: [-3, 3] Domain: (-, ) Range: [0, ) Range: [-3, 3]
Function? Function Not a Function Domain: [0, ) Domain: (-, ) Range: (-, ) Range: (-, )
Function? Function Not a Function Domain: (-, 0] Domain: (-, ) Range: (-, ) Range: (-, 0]
Is Y a function of X? YES! NO! YES! NO!
Functions • A function pairs one object with another. • A function will produce only one object for any pairing. • A function can be represented by an equation.
Functions In order to distinguish one function from another we must name it.
Functions Values that go into a function are independent.
Functions Values that come out of a function are dependent.
Functions • To evaluate the function for a particular value, substitute that value into the equation and solve. • You can evaluate a function for an expression as well as for a number. • To do so, substitute the entire expression into the equation. • Be careful to include parentheses where needed.
Functions Find what y equals when x equals 5. the machine f is a function of x that produces x - squared Find f (5)
Function Notation Variable in the function Name of the function
Composition Functions Given f(x) = 2x – 3 and g(x) = x2 but…
Conclusion • A function is a relationship between two sets that pairs one object in the first set with one and only one object in the second set. • To evaluate the function for a particular value, substitute that value into the equation and solve. • To evaluate the function for an expression, substitute the entire expression into the equation; include parentheses where needed.