Math Problem Statement

Let f=​{(- 4,2​),(-1, 4)(3,0)} and g={(-3,3),(1,3)(2,0)(4,-1)}. Find f(g(x))

Solution

To find f(g(x))f(g(x)), also known as the composition of functions fgf \circ g, we substitute the outputs of g(x)g(x) into the function f(x)f(x).

Given the sets of points for ff and gg:

  • f={(4,2),(1,4),(3,0)}f = \{(-4, 2), (-1, 4), (3, 0)\}
  • g={(3,3),(1,3),(2,0),(4,1)}g = \{(-3, 3), (1, 3), (2, 0), (4, -1)\}

We need to follow these steps:

  1. Identify the value of g(x)g(x) for each xx in the domain of gg.
  2. Substitute these g(x)g(x) values into f(x)f(x), checking if ff is defined for those values.

Step 1: Find g(x)g(x)

  • For x=3x = -3, g(3)=3g(-3) = 3.
  • For x=1x = 1, g(1)=3g(1) = 3.
  • For x=2x = 2, g(2)=0g(2) = 0.
  • For x=4x = 4, g(4)=1g(4) = -1.

Step 2: Find f(g(x))f(g(x))

Now, we substitute the values of g(x)g(x) into f(x)f(x):

  • For g(3)=3g(-3) = 3, we find f(3)f(3). From the definition of ff, f(3)=0f(3) = 0, so f(g(3))=0f(g(-3)) = 0.
  • For g(1)=3g(1) = 3, we find f(3)f(3) again. Thus, f(g(1))=0f(g(1)) = 0.
  • For g(2)=0g(2) = 0, we check if f(0)f(0) is defined, but 00 is not in the domain of ff, so f(g(2))f(g(2)) is undefined.
  • For g(4)=1g(4) = -1, we find f(1)f(-1). From the definition of ff, f(1)=4f(-1) = 4, so f(g(4))=4f(g(4)) = 4.

Conclusion:

The composition f(g(x))f(g(x)) is:

  • f(g(3))=0f(g(-3)) = 0
  • f(g(1))=0f(g(1)) = 0
  • f(g(2))=undefinedf(g(2)) = \text{undefined}
  • f(g(4))=4f(g(4)) = 4

Would you like further details on function composition?


Relative questions:

  1. How do you determine the domain of a composite function?
  2. What happens when a value in g(x)g(x) is not in the domain of f(x)f(x)?
  3. Can you graph fgf \circ g to visualize its behavior?
  4. How would fgf \circ g change if a new point were added to either function?
  5. What is the significance of an undefined value in function composition?

Tip: Always check if the output of g(x)g(x) lies within the domain of f(x)f(x) before evaluating the composite function.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Domain and Range

Formulas

f(g(x)) - Composition of functions

Theorems

Function Composition Theorem

Suitable Grade Level

Grades 10-12