Functions in Mathematics
Explore various ways to represent functions, analyze domains and ranges, and practice composition of functions in math. Learn function definitions and relations with examples in this comprehensive guide.
Functions in Mathematics
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Bell work: • Which of these are ways to represent a function? • f(x)=x+3 • f(x)=+5 • (0,1),(1,2),(2,3),(3,4),(4,5)… • Double a number and add six • The image to the right
What is a function? • In your groups, arrive at a shared definition of what a ‘function’ is. When you’re finished, turn in your group’s definition(with all member’s names) • We will discuss different definitions as a class.
Relations vs functions • A relation is some relationship between inputs and outputs • A function is a relation that matches each input WITH ONLY ONE output
Domain and Range • Domain is the set of all inputs(aka x-values) • Range is the set of all outputs (aka y-values)
What is the domain and range of these functions? • f(x) = 5x+7 • g(x) = 5 • h(x) = • r(x) =
Adding functions • If f(x)=+5, and g(x) = x + 7, what is f(4) + g(4) ? • If h(x)=+12, what is h(4) ?
Adding functions • If f(x)=-2, and g(x) = , what is f(2) + g(2) ? • If h(x)=-2, what is h(2) ?
Subtracting functions • If f(x)=+5, and g(x) = x + 7, what is f(4) - g(4) ? • If f(x)=-2, and g(x) = , what is f(2) - g(2) ?
Multiplying functions • If f(x)=+5, and g(x) = x + 7, what is f(4) * g(4) ? • If f(x)=-2, and g(x) = , what is f(2) * g(2) ?
Dividing functions • If f(x)=+5, and g(x) = x + 7, what is f(4) / g(4) ? • If f(x)=-2, and g(x) = , what is f(2) / g(2) ?
IN GENERAL…what can we say about… • f(x)+g(x)=… • f(x)-g(x)=… • f(x)*g(x)=… • f(x)/g(x)=… (f+g)(x) (f-g)(x) (f*g)(x) (f/g)(x) As long as g(x) does not equal zero
Evaluating functions • If f(x) = 12x+5, what is f(3)? • If f(x) = 12x+5, what is f(y)? • If f(x) = 12x+5, what is f( )?
Evaluating functions • If f(x) = 12x+5, what is f(3+7)?
Composition of functions • The previous example was a composition of functions. Basically, everywhere we had a variable, we replace it with an entirely new function. • This is denoted as ᴑ(x), or as
Homework: • Section 1.1, pages 9-11: 2, 10, 11, 13-15, 38-40, 42, 44, 47 • Section 1.2, pages 17-18: 5-8, 14, 18, 19, 22-24