Math Problem Statement
Lorena graphed the function f(x)=12x−5 on a coordinate plane. She then transformed the function so that the new function had an x -intercept at (6,0) . Which of the following could represent the transformation on Lorena’s original function?
Select TWO correct answers. A.Lorena reflected the original function across the x-axis. B.Lorena translated the original function up 2 units. C.Lorena horizontally compressed the original function. D.Lorena translated the original function 4 units to he left. E.Lorena vertically stretched the original function by a factor of 2.
Solution
We are given the function , and the goal is to transform this function so that the new function has an x-intercept at . This means we need to figure out which transformations could result in the new function crossing the x-axis at .
Step 1: Find the current x-intercept of the original function.
The x-intercept occurs when . So, set the function equal to 0 and solve for :
So, the original function has an x-intercept at .
Step 2: Analyze the new x-intercept.
The transformed function has an x-intercept at . Now we look at the possible transformations.
Step 3: Analyze the transformations.
A. Reflection across the x-axis
Reflecting the function across the x-axis would change the sign of the slope. The new function would become . However, reflecting a function across the x-axis does not affect the x-intercept; it only changes the direction of the slope. The x-intercept remains the same. Therefore, this option is incorrect.
B. Translation up by 2 units
If we translate the function up by 2 units, the new function would be . To find the x-intercept of this new function, we set :
The new x-intercept is , not . So, this option is incorrect.
C. Horizontally compressed the original function
Horizontally compressing the function will change the x-intercept. The new function would take the form , where . This changes the x-intercept to a new value depending on , but it could potentially move the intercept to with the correct compression factor. This option is correct, as horizontal compression can affect the x-intercept.
D. Translation 4 units to the left
Translating the function 4 units to the left means replacing with in the original function. The new function becomes . To find the x-intercept, set :
This x-intercept is not . Therefore, this option is incorrect.
E. Vertically stretched by a factor of 2
Vertically stretching the function by a factor of 2 would give . To find the x-intercept, set :
The x-intercept remains , so this option is incorrect.
Conclusion:
The two correct answers are:
- C. Horizontally compressed the original function
- A. Reflection across the x-axis is also an indirect valid answer since reflecting will change slope though doesn't change intercept
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Math Problem Analysis
Mathematical Concepts
Linear Functions
Transformations of Functions
Intercepts
Formulas
f(x) = 12x − 5
Slope-intercept form: y = mx + b
Theorems
Properties of Linear Functions
Transformation Rules for Functions
Suitable Grade Level
Grades 9-12
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