based on the definition of a real number, what can you eliminate ?
368083
Imaginary and Complex Numbers\n\nDo not let someone argue that all numbers are imaginary...just a side note.
152234
1, 3, 5, 7, 11, 17....\n\n\nNumbers that can only be divided by that number or 1 with the result of a whole number.
629310
nything that doesn't involve either zero or U
795285
first of all, you need to know that there are basically two types of numbers. Real and imaginary. \nreal numbers are those which can be represented in one form or another, but they exist in real world. for example, if you say that there are 4 trees, that means that you can count the number of trees to be a distinct value, ie., 4.\nor consider this. the probability of an event happening is 0.58. this means that the event will be successful 58 times if it is performed 100 times. \nreal numbers consist of all the rational, irrational numbers. that means all these can be realised to be present.\n\nnow coming to imaginary numbers, these are not actually present. \nconsider a number like sqrt(-1). we all know that a square root of a negative number doesnt exist. so, we just say that sqrt(-1) doesnt exist. such numbers can be conveniently represented as Imaginary Numbers. these numbers donot mean anything in the real world, but help in our mathematical calculations.\nnow, hope this answers your question....
203030
its a representation of the actual numbers-----
795252
Let a and b be any two real numbers. Consider the number x defined by\n\nx = ab + (-a)(b) + (-a)(-b).\n\nWe can write\nx = ab + (-a)[ (b) + (-b) ]       (factor out -a)\n  = ab + (-a)(0)\n  = ab + 0\n  = ab.\n\nAlso,\nx = [ a + (-a) ]b + (-a)(-b)      (factor out b)\n  = 0 * b + (-a)(-b)\n  = 0 + (-a)(-b)\n  = (-a)(-b).\n\nSo we have\n      x = ab\nand\n      x = (-a)(-b)\n\nHence, by the transitivity of equality, we have\n\n      ab = (-a)(-b).
922786
For all real numbers x:\n\n\n12 + x = 18\n\n-12 + 12 + x = -12 + 18\n\nx = 6\n\n{6}
1035877
The natural logarithm (over the real numbers) is defined only for positive numbers, so \n\nx-4>0\n\nin other words\n\nx>4.
905755
you must include x=0.
730130
Domain = x... should be all real numbers\n\nRange = y... 2 and up... x can be a negative number, but will always end up being postive when added to two, therefore the lowest number is 2
120877
well i dont fully understand what you mean by structure but the real numbers are pretty much everything that is not imaginary so \n(-infinity,infinity) this includes rationals, irrationals, integers, and natural numbers.  Numbers that are not included are imaginary number (things that have an i attached to it), these numbers occur when you take the square root of -1 (sqrt(-1))\n\nhope that helps
737767
No, it is a real number. \n\nTo factor this write it as \n\n(x - 3)^2 - 5\n\nThis is the difference of 2 squares, (x - 3) and sqrt(5). So the factorization is \n\n((x - 3) + sqrt(5))*((x - 3) - sqrt(5))\n\nIn this form it is easy to see if the answer is real or not, if the right side is nonnegative there are real solutions, if it is < 0 then there are none.
596727
Figure out what other number times itself equals your number.  That's its square root.
550047
rational numbers are numbers that have decimals that end or have decimals that repeat.\n\ne.g. 1.33333333..., 1/3, 2, sq root 4, 3.1212121212..., 3.3233343536\n\nirrational numbers have decimals that cannot be terminated, meaning they can continue on forever.\n\ne.g. pi (mathematical term, not pie for eating!), 3.3233343536... (... is very important because it indicates that the decimals go on, if it doesn't have that then it means decimal ends) sq root 3\n\nhope you understand now :)
169470
The domain is the whole set R (all real numbers) since your function is defined for every x from R.\nSimply, you can put any real number to be x and you will have  real number as an answer.
378164
what do you mean by real. Does something need to be seen to be real? Is the number 6 real? Do you believe that 4 + 4 = 8?
756332
Hi there!\n\nI've heard the name "hyper real" before, but I don't know much about them.  I had a look on the net though, and came up with this link, which looks quite in depth and reliable: http://mathforum.org/dr.math/faq/analysis_hyperreals.html#construction\n\nAlso try having a look on wikipedia, the link is below.\n\nFrom what I can make out from having a quick read of these webpages is that hyperreal numbers include infinite numbers and infinitesimal numbers (i.e. numbers that are smaller than all positive real numbers and greater than all negative real numbers, and it is possible to have non-zero infinitesimal numbers).  \n\nIt helps to understand a little of real analysis, where you have what's known as an epsilon delta definition of the limit of a function, i.e. the real number R is the limit of f (a function from the real numbers to the real numbers) at a if given epsilon greater than zero there exists a delta greater than zero such that if \n0<|x-a|<delta, then |f(x)-R|<epsilon. (where |x-a| means the modulus of x-a, i.e. the [positive] distance between x and a on the real number line).  Basically, this rigorously defines the idea of "getting as close as you like" to the limit, and it was important in the development of calculus, because it put the limit concept on a rigorous setting, and not just an intuitive one.\n\nHowever, according to Wikipedia, Abraham Robinson gave a rigorous definition of infinitely large and infinitely small numbers, in what's known as non-standard analysis, and this is where the hyperreal numbers come in.\n\nHope this is helpful for you!