math: 101

Posers and Puzzles 31 Jan '04 16:30
1. 31 Jan '04 16:30
as my trig class dose not nearly allow me to understand half the poasts on this fourm, can someone explain the diffrence between algibraic and transendual irratinal numbers?
2. 31 Jan '04 19:491 edit
Originally posted by fearlessleader
as my trig class does not nearly allow me to understand half the posts on this forum, can someone explain the difference between algebraic and transcendental irratinal numbers?
minor spelling errors in your message corrected (as if i'm a good one to do that since i make a huge number of typos).
ok, don't say you weren't warned!!
an algebraic number is any real irrational number that is a rational power of an integer, ratinal number, or other algebraic number. examples are: 2^0.5, 4^(2/3), 1001^(1/7), 3072^(16/5), and even something like (2^0.5 + 3^(1/4))^(1/7)--at least i'm fairly sure that last one is in this category. (for this discussion, we're considering real roots of the above numbers, no complex ones.) this set has cardinality (number of elements) equivalent to that of the rational numbers, usually designated as &quot;aleph-null&quot;.
transcendental numbers are the irrational numbers that do not fit the above definition. in this area, you have all logarithms, most of the trig functions, and irrational powers of numbers. two well-known transcendentals are e (the basis of all logarithms, even if they use a different base) and pi (ratio of circumference to diameter of a circle, used mostly in trigonometry). another would be 2^(2^0.5), a number formed by an irrational power. in addition, almost all numbers created by series sums fall into this category. my favorite number in this class is the decimal represented by a 9 in all (2^n) positions and an 8 otherwise; it looks like: 0.9989888988888889... and some of its offshoots. this set is much larger than the algebraics, having cardinality equivalent to that of the reals, usualy written sa &quot;aleph-one&quot; or &quot;C&quot;
the old definition of an irrational number, &quot;a decimal that doesn't terminate and doesn't ever repeat in blocks&quot;, is a simplified way of considering this fascinating set of numbers.
hope that helps!
3. Acolyte
Now With Added BA
02 Feb '04 00:00
Originally posted by BarefootChessPlayer
minor spelling errors in your message corrected (as if i'm a good one to do that since i make a huge number of typos).
ok, don't say you weren't warned!!
an algebraic number is any real irrational number that is a [b]rational power
of an integer, ratinal number, or other algebraic number. examples are: 2^0.5, 4^(2/3), 1001^(1/7), ...[text shortened]... blocks", is a simplified way of considering this fascinating set of numbers.
hope that helps![/b]
An equivalent definition of algebraic numbers is that an algrebaic number is a real solution to P(x) = 0, where P is a polynomial (ie ax^n + bx^n-1 + cx^n-2 .... + yx + z) with integer coefficients. In fact, even if the coefficients in P are arbitrary albegraic numbers, the real solutions will still be algebraic, and all the complex soutions will be of the form A + Bi, where A and B are algebraic.
4. 07 Feb '04 21:04
Originally posted by Acolyte
An equivalent definition of algebraic numbers is that an algrebaic number is a real solution to P(x) = 0, where P is a polynomial (ie ax^n + bx^n-1 + cx^n-2 .... + yx + z) with integer coefficients. In fact, even if the coefficients in P are arbitrary albegraic numbers, the real solutions will still be algebraic, and all the complex soutions will be of the form A + Bi, where A and B are algebraic.
i think barefood did me a bit more good, but thanks anyway.ðŸ™‚

now that i have a clue, next question: what is a logerithum?
5. !~TONY~!
1...c5!
08 Feb '04 00:01
Your Math 101 class should have covered logarithms (hopefully). You sure you don't know what they are?? Examples: log 25, log 15, or natural logs! Examples ln 25, ln 15.
6. 08 Feb '04 16:402 edits
Originally posted by fearlessleader
i think barefood did me a bit more good, but thanks anyway.ðŸ™‚

now that i have a clue, next question: what is a logerithum?
you might think of a logarithm this way.
take any two real positive numbers, a and b, then ask, &quot;to what power do i need to raise a to get b?&quot;. for staters, we'll use 2 and 0.25. to what power do we need to raise two to get one fourth? the answer is -2, since 2^(-2) = 1/2^2, which is 1/4. we would write &quot;log[2] 1/4 = -2,&quot; where the number in brackets indicates the number, in this case 2, of which we are trying to find the power (this is ordinarily done using subscripts but i don't have that option here); this number is called the base.
how about log[10] 5000? here we see the additive property of logs. if we cube ten, we get 1000. to get 5000, we raise it to the log[10] 5, which is almost .7, so in very rough terms, the answer is 3.7. (the actual value is a transcendental number slightly less than 3.7.)
pleae note that 1 is the zero power of any other positive number so log[a] 1 = 0 for all positive real a.
here is an intresting side light: all logarithms are based on the transcendental number e (roughly 2.718281828459...), regardless of their actual base. the only difference is that, to get any other base, you take reciprocal of log[e] of the base (a above) and multiply by log[e] of the number b above. to simplify notation, the operation &quot;log to base e&quot; is written &quot;ln&quot; or &quot;ln&quot; by most authors but i learned a different way. using this, we could write log[2] 8 as (ln 8)/ln 2. it will still be 3.
thoroughly confused yet: ðŸ™‚
7. 10 Feb '04 12:35
Originally posted by BarefootChessPlayer
you might think of a logarithm this way.
take any two real positive numbers, a and b, then ask, "to what power do i need to raise a to get b?". for staters, we'll use 2 and 0.25. to what power do we need to raise two to get one fourth? the answer is -2, since 2^(-2) = 1/2^2, which is 1/4. we would write "log[2] 1/ ...[text shortened]... g this, we could write log[2] 8 as (ln 8)/ln 2. it will still be 3.
thoroughly confused yet: ðŸ™‚
i sure am!ðŸ˜€

i'll read it though a few dozen times until i have a clue.
8. Fiathahel
Artist in Drawing
10 Feb '04 13:321 edit
Log[n](x) is just the inverse of n^x.

so if b = n^t then log[n] b = t

What does 101 mean?
9. TheMaster37
Kupikupopo!
10 Feb '04 19:32
5
10. 11 Feb '04 03:473 edits
Originally posted by Fiathahel

What does 101 mean?
the first course of a subject in u. s. colleges is usually numbered 101.
some colleges start their courses at 1, but most universities i've seen have their beginning courses at 101, and anything below that is &quot;remedial&quot; material.
11. 12 Feb '04 16:27
explain this concept of &quot;e&quot;
12. 12 Feb '04 23:044 edits
Originally posted by fearlessleader
explain this concept of e
the transcendental number e is most simply derived as the sum of the reciprocals of the factorials of integers starting with zero (remember, 0! = 1! =1). in sum notation (as modified for the keyboard): sum(n=0 to infinity) (1/n!).
this will produce about 2.718281828459....
there are two other ways of reaching it: the limit as x goes to zero of (1+x)^(1/x) or, as x goes to infinity, of (1 + 1/x)^x, a case of 1^infinity.
the function e^x is called the exponential function and is written often as exp x or exp(x), and is the only nonlinear function which is its own derivative.
the inverse of exp x is ln x--the number you to which you must raise e to get x.
13. Fiathahel
Artist in Drawing
13 Feb '04 10:43
Originally posted by BarefootChessPlayer
the transcendental number e is most simply derived as the sum of the reciprocals of the factorials of integers starting with zero (remember, 0! = 1! =1). in sum notation (as modified for the keyboard): sum(n=0 to infinity) (1/n!).
this will produce about 2.718281828459....
there are two other ways of reaching it: the limit as x go ...[text shortened]...
the inverse of exp x is ln x--the number you to which you must raise e to get x.
lim{x-&gt;inf} (1+1/x)^x is the best (most common) way to define e, and has the advantage that lim{x-&gt;inf} (1+t/x)^x = e^t.

also sum{n=1 to inf} t^n/(n!) = e^t
with which it is easy to prove it is its own derivative.

14. 13 Feb '04 15:381 edit
Originally posted by Fiathahel
lim{x->inf} (1+1/x)^x is the best (most common) way to define e, and has the advantage that lim{x->inf} (1+t/x)^x = e^t.

also sum{n=1 to inf} t^n/(n!) = e^t
with which it is easy to prove it is its own derivative.

i agree, except i think the last expression should start with n=0, rather than 1.

the frist way i learned it was lim(x-&gt;0) (1+x)^(1/x), and subsitutting y=1/x gives the corresponding formula.
it wsa somewhat after that that i learned the factorial formulae for e^x, sin x, cos x, tan x, etc., and that e^(2*pi*i) = 1.
15. 23 Feb '04 16:31
Originally posted by BarefootChessPlayer
the transcendental number e is most simply derived as the sum of the reciprocals of the factorials of integers starting with zero (remember, 0! = 1! =1). in sum notation (as modified for the keyboard): sum(n=0 to infinity) (1/n!).
this will produce about 2.718281828459....
there are two other ways of reaching it: the limit as x go ...[text shortened]...
the inverse of exp x is ln x--the number you to which you must raise e to get x.
i understand (the first parts at least)

new line: how dose one find the system max of a system of non-linear inequalities?