Math Problem Statement

when describing transformations how do you write the equation of a graph

Solution

To write the equation of a transformed graph, you need to consider how each transformation affects the parent function. Transformations include translations, reflections, stretches, and compressions. Here is a general way to write the equation of a transformed graph based on different types of transformations:

General form of a transformed function:

For a given function f(x)f(x), the transformation can be written as:

g(x)=af(b(xh))+kg(x) = a \cdot f(b(x - h)) + k

Where:

  • aa: Vertical stretch/compression or reflection factor. If a>1|a| > 1, it stretches the graph vertically. If 0<a<10 < |a| < 1, it compresses vertically. If a<0a < 0, it reflects over the x-axis.
  • bb: Horizontal stretch/compression or reflection factor. If b>1|b| > 1, it compresses the graph horizontally. If 0<b<10 < |b| < 1, it stretches horizontally. If b<0b < 0, it reflects over the y-axis.
  • hh: Horizontal translation (shift). Positive hh shifts the graph to the right, negative hh shifts it to the left.
  • kk: Vertical translation (shift). Positive kk shifts the graph upward, negative kk shifts it downward.

Examples:

  1. Vertical shift: If you have f(x)=x2f(x) = x^2, shifting it up by 3 units would be written as: g(x)=f(x)+3=x2+3g(x) = f(x) + 3 = x^2 + 3

  2. Horizontal shift: If you shift f(x)=xf(x) = \sqrt{x} to the right by 2 units: g(x)=f(x2)=x2g(x) = f(x - 2) = \sqrt{x - 2}

  3. Reflection across the x-axis: Reflecting f(x)=sin(x)f(x) = \sin(x) across the x-axis: g(x)=sin(x)g(x) = -\sin(x)

  4. Vertical stretch by a factor of 2: Stretching f(x)=ln(x)f(x) = \ln(x) vertically by a factor of 2: g(x)=2ln(x)g(x) = 2\ln(x)

  5. Combining multiple transformations: Reflecting f(x)=x3f(x) = x^3, shifting it 3 units left and 4 units up: g(x)=f(x+3)+4=(x+3)3+4g(x) = -f(x + 3) + 4 = -(x + 3)^3 + 4

Summary:

The function g(x)=af(b(xh))+kg(x) = a \cdot f(b(x - h)) + k encapsulates the transformation of the parent function f(x)f(x) based on shifts, stretches, compressions, and reflections.

Would you like further details or have any questions?

Five questions to expand:

  1. How do horizontal and vertical stretches affect the graph differently?
  2. What happens if you apply both horizontal and vertical translations together?
  3. How do you write the equation for a reflection over the y-axis?
  4. What effect does a negative value for bb have on the graph?
  5. How can we combine multiple transformations in a single equation?

Tip:

To visualize transformations, start with the basic parent function and apply each transformation step-by-step (stretch, shift, reflect).

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Math Problem Analysis

Mathematical Concepts

Functions
Graph Transformations
Algebra

Formulas

g(x) = a * f(b(x - h)) + k

Theorems

Transformation of functions

Suitable Grade Level

Grades 9-12