Wikipedia:Reference desk/Archives/Mathematics/2007 September 17

= September 17 =

parabolica
Is the word parabolica a real word i.e. a derivative of parabola (geometry)? —Preceding unsigned comment added by 210.79.26.193 (talk) 05:42, 17 September 2007 (UTC)


 * The adjective parabolic is parabolica in some languages; it can be transliterated Classical Greek, Latin, and Italian (see, e.g., Traiettoria parabolica). With an accent like this: parabólica, it is Spanish (Castilian), while parabòlica is Catalan. It is not a common English word. --Lambiam 06:20, 17 September 2007 (UTC)


 * Anothere example of Italian usage is the "Parabolica" bend at the Monza Grand Prix circuit - bend 9 on this diagram. Gandalf61 09:00, 17 September 2007 (UTC)
 * Sounds like an artistic use - such as a abstract quadratic sculptor's exhibition of 'parabolica' cf eclectica etc87.102.79.48 11:23, 17 September 2007 (UTC)

logathrims - i dont get it (basic)
for example simplify $$ \dfrac{\log 8}{\log 0.25}$$

so far what ive done is log 4^1.5 / log 4^-1 which is (1.5 log 4 / -1 log 4) which gives me log -1.5 and the answer is meant to be log -3/2. Any ideas?? thanks Testeretset 13:58, 17 September 2007 (UTC)


 * Call me crazy, but I think that -1.5 = -3/2. However, it should be just -1.5 (or -3/2), not log -1.5 or log -3/2. -- Meni Rosenfeld (talk) 14:20, 17 September 2007 (UTC)


 * Agree with Meni, and for your original question, can you rephrase both numerator and denominator as log(2^x) ? Capuchin 14:23, 17 September 2007 (UTC)

makes sense, yeah the answer was just -3/2 my mistake. thanks... Testeretset 14:34, 17 September 2007 (UTC)

I suggest that the problem lies NOT with logarithms but with faulty mis-understanding of the relationship between rational numbers and floating point numbers. One wonders why the questioner did not take the further step of dividing -3 by 2 on their scientific calculator. 202.168.50.40 00:42, 18 September 2007 (UTC)


 * 1.5 is not a floating-point number. Floating point is the name of a method for storing numbers on a computer in two parts, a mantissa and an exponent. The location of the decimal point can be easily changed by changing the exponent part (hence the name, "floating point").
 * On the other hand, both 3/2 and 1.5 are rational; you might call the former a "fraction" and the latter a "decimal number" (though I wouldn't expect to encounter such terms in any serious mathematics). -- Meni Rosenfeld (talk) 02:28, 18 September 2007 (UTC)