JIMJONESBALLIN | anubiss, use brackets for open intervals. (5, +infty) |

anubiss | sorry k |

me22 | "anubiss> but if the domain is ok on the denominator, it wil be ok on the numerator for sure..." <-- not necessarily. Sqrt[x]/(|x|+1) the denominator is "good" everywhere, but the numerator isn't. so the domain is [0,inf) despite the denominator being defined for all |R |

anubiss | k is it possible to calculate the derivative of an absolute function ^ ? |

me22 | not at the "corner" |

anubiss | complicate stuff |

me22 | you just do the 2 parts separately |

anubiss | then id write +- |

me22 | d|x|/dx = { 1 for x >0, -1 for x <0 } |

anubiss | is the use of the conjugate is ok? |

me22 | ? |

anubiss | say i want to calculate a limit lim x->1 (sqrt(x) - 1 ) / (x-1) i would do |

ihope | My simple set theory has one axiom. |

anubiss | lim x->1 (sqrt(x) - 1 ) / (x-1) * (sqrt(x) +1) / (sqrt(x) +1) |

ihope | Comprehension: given a predicate on sets, there is a set containing exactly those sets matching the predicate iff the predicate doesn't match as many sets as p(x) = T does. Of course, you might want to add more axioms to it, like one guaranteeing the existance of sets. This one axiom doesn't guarantee any. |

__mikem | does anyone know why applying the rische integration algorythm on tan x doesn't give ln(sec x) |

Kasadkad | __mikem: What does it give? |

__mikem | ln(some long expression that definitely does NOT equal sec x) |

Kasadkad | You sure it doesn't? |

ihope | % Integrate[Tan[x]] |

mbot | ihope: Integrate::argmu: Integrate called with 1 argument; 2 or more arguments are expected. Integrate[Tan[x]] |

ihope | Well, that sure didn't give Log[Sec[x]] :-P |

diseaser | is there an easy algebraic rule for factoring something like: x^4 - 1 ? |

me22 | ihope : you forgot the ,x |

__mikem | log(sin(2*x)^2+cos(2*x)^2+2*cos(2*x)+1)/2 this is what maxima got |

me22 | diseaser : difference of squares |

ihope | My guess is this Rische integration algorithm isn't plain old integral. |

me22 | anubiss : that's not a conjugate. |

diseaser | me22: cool thanks |