TRWBW | ? ConcernedWithSec: go with god |

ConcernedWithSec | how old are you guys? |

thermoplyae | 19 and getting older every second |

TRWBW | PuppiesOnAcid: so if they are all 3 different points, and no 2 of them are verticle, than you can compute slope A to B and slope B to C, and they are on the same line if and only if those are equal PuppiesOnAcid: with me on the 2D case? |

PuppiesOnAcid | Yep |

TRWBW | PuppiesOnAcid: so now in 3D. well slope=rise/run. where run is change in x and rise is change in y, yes? PuppiesOnAcid: (that is in 2D that's what slope is) |

PuppiesOnAcid | yes |

TRWBW | PuppiesOnAcid: so in 3D you can think of two slopes, slope_y and slope_z. slope_y is (change in y)/(change in x) and slope_z=(change in z)/(change in x) PuppiesOnAcid: and the 3 points will be collinear if slope_y(A,B)=slope_y(A,C) *and* slope_z(A,B)=slope_z(A,C) |

PuppiesOnAcid | Got it |

TRWBW | PuppiesOnAcid: unfortunately, it gets more complicated if any of those (change in x)=0. that's like the verticle case in 2D, but in 3D its worse |

PuppiesOnAcid | I am pretty sure that is not the case. |

TRWBW | PuppiesOnAcid: then you are fine |

netpro25_ | anyone know how to find the sum of the series? sum(n=0..oo, (1/(2^n)) |

TRWBW | netpro25_: it's a geometric series, they should cover that in your book netpro25_: i could give you the formula, or try to show you where it comes from |

netpro25_ | k i am stuck on the algebra let me show you |

TRWBW | ? |

netpro25_ | i gave you the wrong problem hold on sum(n=0..oo, (1/(2^n) - (1/(3^n)) i got the divided into two sums |

TRWBW | k same thing before, it's geometric sums |

netpro25_ | do you plug in oo? |

TRWBW | that means a sum of the form a_n=b*r^n you got 1/2^n=1*(1/2)^n and 1/3^n=1*(1/3)^n but in either case the formula is b/(1-r) |

netpro25_ | k i see it ah i see thanks trwbw you the man |

TRWBW | np |

jadenbane | What's a quick check to see if teo matricies are similar. detA=detB? Or do I have to find the eigenvalues of both? |

Kasadkad | That's a necessary but not sufficient condition |