Linear transformations are easy to graph. The key principles are these:

- A transformation outside the function acts vertically, while a transformation inside the function acts horizontally;
- Adding and subtract shift the graph, while multiplying and dividing change the scale;
- Anything inside (horizontal) acts
*backwards*.

More concretely, consider these examples:

Transformation of f: |
Effect on the graph: |
---|---|

f(x) + 3, |
Shift 3 units upwards; |

f(x) − 3, |
Shift 3 units downwards; |

2f(x), |
Stretch vertically by a factor of 2; |

f(x)/2, |
Compress vertically by a factor of 2; |

−f(x), |
Flip vertically across the horizontal axis; |

−2f(x), |
Flip and stretch vertically; |

2f(x) + 3, |
Stretch vertically and then shift upwards; |

f(x + 3), |
Shift 3 units to the left; |

f(x − 3), |
Shift 3 units to the right; |

f(2x), |
Compress horizontally by a factor of 2; |

f(x/2), |
Stretch vertically by a factor of 2; |

f(−x), |
Flip horizontally across the vertical axis; |

f(−2x), |
Flip and compress horizontally; |

f(2x + 3), |
Shift to the left and then compress horizontally. |

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This web page was written in 2010 by Toby Bartels, last edited on 2010 November 28. Toby reserves no legal rights to it.

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