Math Problem Statement

show all your steps like how you would write on a test on how you got the answer

The graph of y = x^2 is horizontally stretched by a factor of 2, reflected in the x-axis, and shifted 3 units down. Find the equation that results from the transformation, and graph it.

Solution

We are given the function y=x2y = x^2 and asked to apply several transformations to it:

  1. Horizontally stretch the graph by a factor of 2.
  2. Reflect the graph in the x-axis.
  3. Shift the graph 3 units down.

Step-by-step transformation process:


Step 1: Horizontal Stretch by a factor of 2

A horizontal stretch by a factor of 2 means we replace xx with x2\frac{x}{2}. The transformation for horizontal stretching is:

y=(x2)2=x24y = \left( \frac{x}{2} \right)^2 = \frac{x^2}{4}

So, after this transformation, the equation becomes: y=x24y = \frac{x^2}{4}


Step 2: Reflection in the x-axis

A reflection in the x-axis means we multiply the entire function by 1-1. Applying this to y=x24y = \frac{x^2}{4}:

y=x24y = -\frac{x^2}{4}


Step 3: Shift 3 units down

To shift the graph 3 units down, we subtract 3 from the function. Applying this to y=x24y = -\frac{x^2}{4}:

y=x243y = -\frac{x^2}{4} - 3


Final Equation:

The final transformed equation is:

y=x243y = -\frac{x^2}{4} - 3


Graphing the Transformed Equation:

To graph y=x243y = -\frac{x^2}{4} - 3:

  1. Shape: This is a parabola that opens downward (due to the negative sign).
  2. Stretching: The parabola is wider than the basic y=x2y = x^2 because of the horizontal stretch by a factor of 2.
  3. Shift: The vertex is located at (0,3)(0, -3), since the graph has been shifted 3 units downward.
  4. Reflection: The graph is upside-down because of the reflection across the x-axis.

Would you like me to graph this for you?


Follow-up Questions:

  1. How do horizontal stretches affect the width of a parabola?
  2. What does reflecting a function in the x-axis do to its graph?
  3. How does shifting a graph vertically influence the equation?
  4. Can you explain how to determine the vertex of the transformed parabola?
  5. What would the equation be if instead of shifting down, we shifted the graph upwards by 3 units?

Tip:

Always apply transformations in the correct order: stretch/shrink first, then reflect, and finally shift.

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Math Problem Analysis

Mathematical Concepts

Transformations of Functions
Quadratic Equations

Formulas

Horizontal Stretch: y = f(ax)
Reflection in x-axis: y = -f(x)
Vertical Shift: y = f(x) + c

Theorems

Transformation of Functions

Suitable Grade Level

Grades 9-12