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# Module25

### How to use common logarithms, natural Logarithms and the change of base formula.

Question | Answer |
---|---|

What are Common Logarithms? | logarithms to base 10, written as log x. |

What are Natural Logarithms? | logarithms to base e, written as ln x. |

What is a logarithm? | A logarithm is an exponent. |

What is the change base formula? | The change base formula is log x =logx/logb and it only works if a,b, and c are positive numbers and neither b nor c is equal to 1. |

How do you enter a logarithm with a different base on a graphing calculator? | using the change base formula log(x)/log(b) |

What is another way of writting logx=y | x=10^y |

How do you evaluate log64 with base 2? | log(64)/log(2)= 6 |

How do you evaluate ln 1 ? | ln(1)=0 |

How do you find x in log x=1.8? | Rewrite the equation in exponent form and solve for x.Since we know the equation is common logarithm we know the base is 10 so x=10^1.8~63.0957 |

How do you find x in ln x=2? | Rewrite the equation in exponent form and solve for x. Since it's a natuaral logarithm we know that the base is e. so x=e^2~7.3890 |

Created by:
irenamuco