clarity_ | i used them for diff eq though |

TRWBW | clarity_: in a lot of ways it turns out easier to do calculus with complex numbers, fewer special cases |

gaten | Question: "when a cold drink is taken from a fridge, its temperature is 5 deg C. After 25 mins in a 20 deg C room its temperature has increased to 10 deg C. What is the temp of the drink after 50 mins, and when will the temp reach 15 deg C." I know i have to use newtons' cooling equation, but im stuck |

thermoplyae | Stuck where |

clarity_ | is it normal to go through 3 calc classes without being exposed to calc w/ complex numbers? |

whaleofconfusion | yes |

gaten | thermoplyae: the whole thing really. so far ive only got that dT/dt = k(T - R), T being the temp of the drink, and R being the temp of the room |

whaleofconfusion | i mean normally you'd see a little but not very much |

gaten | i tried solving for k by integrating that equation, but i don't think that's right |

whaleofconfusion | it is right what is the numeric value of the integral of dT/dt from 0 to 25 mins? |

gaten | 25 |

whaleofconfusion | no |

gaten | whaleofconfusion: you mean solve for k? |

whaleofconfusion | yes the answer is 5 not k, but for the integral of dT/dt from 0 to 25 the temperature increased from 5 degrees to 10 degrees |

gaten | right. i plugged in T and R with 10 and 20 |

whaleofconfusion | T is a function of t |

gaten | ok right. temp is dependant on time |

merus | TRWBW: On your advice I tried xdvi, and you're right, it's 5 times faster than any pdf viewer I have. |

soars | http://textpaste.net/mj8e16 |

whaleofconfusion | you don't plug in a value for it when you integrate the left side from 0 to 25 you get 5 when you integrate the right side you get something involving various constants, and k and you set taht equal to 5 |

gaten | wait, the left side is dT/dt which the integral is T, isnt it? |

whaleofconfusion | yes and evaluated from 0 to 25 |

gaten | (25) - (0) = 25...? |

whaleofconfusion | no is that how you evaluate a definite integral? |

soars | This is How Real Men Code .. |

gaten | int(dT/dt) = T(b-a) right? |

whaleofconfusion | no what is the integral of f from a to b, given that the indefinite integral of f is F? |

gaten | F(b)-F(a) |

whaleofconfusion | now use that hint: f = dT/dt |

gaten | oooh ic. T is a function of time, like you told me. so its T(25) - T(0) = 10 - 5 |