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Laura and Becky are each graphing a transformation of the parent cosine function.

- Laura's function is a transformation where the parent function is horizontally compressed by a factor of [tex]$\frac{1}{3}$[/tex] and is reflected over the [tex]$x$[/tex]-axis.
- Becky's function is defined by the equation [tex]$f(x)=3 \cos (x-\pi)$[/tex].

Determine which graph belongs to each student.



Answer :

Sure, let's determine the transformations for each student's function step-by-step to identify their graphs.

### Step-by-Step Solution:

1. Laura's Function:

- Horizontal Compression by a Factor of [tex]\( \frac{1}{3} \)[/tex]:
The parent cosine function is [tex]\( \cos(x) \)[/tex]. When it is horizontally compressed by a factor of [tex]\( \frac{1}{3} \)[/tex], the new function will be [tex]\( \cos(3x) \)[/tex]. This is because compressing horizontally by [tex]\( \frac{1}{3} \)[/tex] means multiplying the input by 3.

- Reflection Over the [tex]\( x \)[/tex]-Axis:
Reflecting a function over the [tex]\( x \)[/tex]-axis changes the sign of the function. Therefore, [tex]\( \cos(3x) \)[/tex] will become [tex]\( -\cos(3x) \)[/tex].

So, Laura's transformed function is [tex]\( y = -\cos(3x) \)[/tex].

2. Becky's Function:

- Equation Given:
Becky’s function is defined by the equation [tex]\( f(x) = 3 \cos (x - \pi) \)[/tex].

- Transformation Details:
The given equation includes a cosine function shifted horizontally and scaled vertically:
- Horizontal Shift: The term [tex]\( (x - \pi) \)[/tex] represents a shift to the right by [tex]\( \pi \)[/tex] units.
- Vertical Scaling: The coefficient 3 in front of the cosine function scales the amplitude by 3.

So, Becky's transformed function is [tex]\( y = 3\cos(x - \pi) \)[/tex].

By understanding these transformations, we can match each function to its respective graph:

Laura’s function is [tex]\( y = -\cos(3x) \)[/tex].
Becky’s function is [tex]\( y = 3\cos(x - \pi) \)[/tex].