Math Problem Statement

Graph f(x) = 3⌈x⌉ + 9.

Solution

The function provided is f(x)=3x+9f(x) = 3 \lceil x \rceil + 9, where x\lceil x \rceil represents the ceiling function, which rounds up xx to the nearest integer greater than or equal to xx. This results in a step function that moves in discrete jumps.

Understanding the graph of f(x)=3x+9f(x) = 3 \lceil x \rceil + 9:

  1. The graph will have discrete points for each integer value of xx.
  2. At each integer xx, the value of f(x)f(x) increases by a jump of 3 units because of the factor 33.
  3. The overall vertical shift of the graph is by 9 units, so all steps begin from 9.

Let's break it down for various values of xx:

  • When x=0x = 0, f(x)=3(0)+9=9f(x) = 3(0) + 9 = 9.
  • When x=1x = 1, f(x)=3(1)+9=12f(x) = 3(1) + 9 = 12.
  • When x=2x = 2, f(x)=3(2)+9=15f(x) = 3(2) + 9 = 15.
  • And so on, increasing by 3 for each unit change in xx.
  • On the negative side, the graph will have a similar pattern: for example, x=1x = -1 gives f(x)=3(1)+9=6f(x) = 3(-1) + 9 = 6.

Analyzing the Graph Choices:

From the four choices in the image:

  • Graph a: This graph appears to show steps in the correct direction but is shifted too far right and up.
  • Graph b: This shows incorrect behavior for negative values and is not a correct match.
  • Graph c: This seems to represent a correct step function with jumps of 3 units and a vertical shift starting at 9.
  • Graph d: Incorrect as the steps aren't consistent with the expected pattern.

Conclusion:

The correct graph that matches the function f(x)=3x+9f(x) = 3 \lceil x \rceil + 9 is Graph c.


Do you need further details or have any questions?

Here are 5 questions to deepen your understanding:

  1. How does the ceiling function x\lceil x \rceil impact the shape of the graph?
  2. What would the graph look like if it used the floor function x\lfloor x \rfloor instead?
  3. How would the graph change if the vertical shift was different, say f(x)=3x+5f(x) = 3 \lceil x \rceil + 5?
  4. Can you explain why the graph increases by steps of 3?
  5. How would the graph behave for non-integer values of xx?

Tip: When graphing step functions, always pay attention to how rounding (floor or ceiling) affects the function's behavior at integer and non-integer values.

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Math Problem Analysis

Mathematical Concepts

Step Functions
Ceiling Function
Vertical Shifts

Formulas

f(x) = 3⌈x⌉ + 9

Theorems

Ceiling function property: ⌈x⌉ rounds x to the smallest integer greater than or equal to x.

Suitable Grade Level

Grades 9-12