Periodic Functions Unit Test Part 2

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Question
Identify the transformations for the function f(x)=3cos(−x+π3)−2.(1 point)
Responses

vertical stretch by a factor of 3, horizontal compression by −1, horizontal shift right by π3, and vertical shift down 2
vertical stretch by a factor of 3, horizontal compression by negative 1 , horizontal shift right by Start Fraction pi over 3 End Fraction , and vertical shift down 2

vertical stretch by a factor of 3, reflection over the y-axis, horizontal shift right by π3, and vertical shift down 2
vertical stretch by a factor of 3, reflection over the y -axis, horizontal shift right by Start Fraction pi over 3 End Fraction , and vertical shift down 2

vertical stretch by a factor of 3, reflection over the y-axis, horizontal shift right by π3, and vertical shift up 2
vertical stretch by a factor of 3, reflection over the y -axis, horizontal shift right by Start Fraction pi over 3 End Fraction , and vertical shift up 2

vertical stretch by a factor of 3, reflection over the y-axis, horizontal shift left by π3, and vertical shift down 2
vertical stretch by a factor of 3, reflection over the y-axis, horizontal shift left by Start Fraction pi over 3 End Fraction , and vertical shift down 2
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1 answer

To identify the transformations for the function \( f(x) = 3\cos(-x + \frac{\pi}{3}) - 2 \), we can analyze each component of the function.

  1. Vertical Stretch: The coefficient 3 indicates a vertical stretch by a factor of 3.

  2. Reflection: The negative sign before x indicates a reflection over the y-axis. This is because when you have \( \cos(-x) \) rather than \( \cos(x) \), it reflects the graph horizontally.

  3. Horizontal Shift: The term \(-x + \frac{\pi}{3}\) can be rewritten as \(-1(x - \frac{\pi}{3})\), which indicates a horizontal shift. The fact that it is \( -x + \frac{\pi}{3} \) means there is a shift to the right by \(\frac{\pi}{3}\).

  4. Vertical Shift: The \(-2\) indicates a vertical shift downwards by 2 units.

Putting this all together, the transformations for the function are:

  • Vertical stretch by a factor of 3
  • Reflection over the y-axis
  • Horizontal shift right by \(\frac{\pi}{3}\)
  • Vertical shift down by 2

Thus, the correct response should be:

vertical stretch by a factor of 3, reflection over the y-axis, horizontal shift right by \(\frac{\pi}{3}\), and vertical shift down 2.