Mathematics
Grade 12
15 min
Add, subtract, multiply, and divide functions
Add, subtract, multiply, and divide functions
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1
Introduction & Learning Objectives
Learning Objectives
Define and notate the sum, difference, product, and quotient of functions.
Compute the algebraic expressions for (f+g)(x), (f-g)(x), (f*g)(x), and (f/g)(x) given f(x) and g(x).
Evaluate combinations of functions at a specific numerical value, such as (f+g)(2).
Determine the domain of a new function created by adding, subtracting, or multiplying two functions by finding the intersection of their original domains.
Determine the domain of a quotient of two functions, ensuring the denominator is not equal to zero.
Apply the concept of function operations to model and solve contextual problems.
Ever wondered how a company combines its revenue and cost functions to find its profit function? 📈 It's just a simple subtraction of functions!
Just like numbers...
2
Key Concepts & Vocabulary
TermDefinitionExample
Sum of FunctionsThe new function created by adding the outputs of two functions, f(x) and g(x), for every x-value in their common domain.If f(x) = x^2 and g(x) = 2x, then the sum function is (f+g)(x) = x^2 + 2x.
Difference of FunctionsThe new function created by subtracting the outputs of two functions, f(x) and g(x), for every x-value in their common domain.If f(x) = 3x + 5 and g(x) = x + 1, then the difference function is (f-g)(x) = (3x + 5) - (x + 1) = 2x + 4.
Product of FunctionsThe new function created by multiplying the outputs of two functions, f(x) and g(x), for every x-value in their common domain.If f(x) = x and g(x) = x - 7, then the product function is (f*g)(x) = x(x - 7) = x^2 - 7x.
Quotient of FunctionsThe new function created by dividing the outputs of...
3
Core Formulas
Sum Rule
(f+g)(x) = f(x) + g(x)
To find the sum of two functions, add their expressions. The domain of (f+g) is the intersection of the domains of f and g, written as D_f ∩ D_g.
Difference Rule
(f-g)(x) = f(x) - g(x)
To find the difference, subtract the second function's expression from the first. The domain of (f-g) is the intersection of the domains of f and g, D_f ∩ D_g.
Product Rule
(f \cdot g)(x) = f(x) \cdot g(x)
To find the product, multiply their expressions. The domain of (f*g) is the intersection of the domains of f and g, D_f ∩ D_g.
Quotient Rule
\left(\frac{f}{g}\right)(x) = \frac{f(x)}{g(x)}
To find the quotient, divide the first function's expression by the second. The domain is the intersection of the domains of f and g, excluding any...
4 more steps in this tutorial
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Sign Up Free to ContinueSample Practice Questions
Easy
Which of the following correctly defines the notation (f+g)(x)?
A.f(g(x))
B.f(x) + g(x)
C.f(x) â‹… g(x)
D.f(x) - g(x)
Easy
Given f(x) = 2x + 1 and g(x) = x - 5, what is (f+g)(x)?
A.3x - 4
B.2x - 4
C.3x + 6
D.x + 6
Easy
Let f(x) = x^2 and g(x) = 3x. What is the value of (g-f)(2)?
A.10
B.4
C.-2
D.2
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