## V

## Term |
## Definition |

V | Roman Numeral for 5 |

variable | subject to change. A letter or a symbol used to represent a number. For example in the expression 2x + 3 = 9, x is the variable |

varies | if x varies directly with y, then x α y and so x = ky, where k is the constant of variation |

varies inversely | if x varies inversely with y then x α ^{1}/_{y} and so x = ^{k}/_{y}, where k is the constant of variation |

velocity | speed. The rate of change of distance over time. V = ^{dx}/_{dt} |

Venn diagrams | the name given to diagram to represent two or more sets, most commonly used in probability |

vertex | corner of a shape |

vertex of a parabola | x coordinate = –^{b}/_{2a} |

vertical | a line that is straight up and down, perpendicular to horizontal |

vertical line test | if a vertical line is drawn through a graph and it cuts the graph at only one point, the graph is said to be a function. If it cuts more than once, it is not a function. In the first diagram the red line cuts the curve in two places, therefore it is not a function. In the second diagram it only cuts it once, therefore it is a function. |

vertically opposite | vertically opposite angles are equal to each other |

vinculum | the line in a fraction separating the numerator (top) from the denominator (bottom) |

volume | the amount of space a 3d shape takes up. Formulas for volume vary from shape to shape, the most basic being for a rectangular prism where V = ℓbh |

vulgar fraction | another term for common fraction, any fraction with a numerator (top) and a denominator (bottom) |