Easy to overlook the answer"Fact is stranger than fiction， we also have many interesting mathematical For example， in the ninth book， I now have a problem in the workbook， education， said: "this is a passenger train to the west， the east from 45 kilometers per hour line， stop， then after 5 hours just what the halfway point of the two cities from 18 km， two things WangXing? How many kilometres from town with the small English in this problem， the calculation method and the results are not the XingSuan king of the number of kilometers than small calculates km less， but the results of the two to This is why? You want to come? You count them two listed in the " Actually， this problem is we can very quickly made a kind of method is: 45 x 5 = 5 (km)， 5 + 18 = 5 (km)， 5 * 2 = 261 (km)， but look close scrutiny， he felt something was Actually， here we overlooked a very important conditions， "this is just what the halfway point of the city from the conditions of 18 kilometers away from" the word "， not to say， or more than halfway If it is not from the middle point to 18 kilometre， column type is the front， if is a kind of more than 18 kilometers halfway， column type should is 45 by 5 = 5 (km)， 5-18 = 5 (km)， 5 x 2 = 189 (km) So the correct answer is: 45 x 5 = 5 (km)， 5 + 18 = 5 (km)， 5 * 2 = 261 (km) and 45 x 5 = 5 (km)， 5-18 = 5 (km)， 5 x 2 = 189 (km) Two answers， WangXing answers with the small English answer is In the daily learning， often have many problems， aim to answer is more in practice or neglected in the exam， we need to carefully examines the topic is， life experience， close scrutiny， correct understanding of Otherwise easily overlooked the mistake， the About "0"0， it is the earliest human contact Our ancestors started only know no and have no is 0， 0， so did? Remember the elementary school teacher once said， "any number of minus itself is equal to 0， 0 means without " That is simply not We all know that the 0 degrees centigrade thermometer said the freezing point of water ( a standard under the pressure of the mixture of water temperature)， including 0 is solid and liquid water But in Chinese characters， 0 means that a zero， such as: 1 more pieces)， Decimal 2) not certain Thus， we know that the "no amount is 0， but not without number， 0 solid and liquid said the differentiator， ""Any divided by " no significance for This is the primary school teacher still talking to a conclusion about the "0"， then the division (primary) is divided into several copies will be a， how much A whole cannot into a "0" no Then I realized the a / 0 0 0 to limit can be expressed in the variable (a variable in the process of changing its absolute than any small forever is positive)， shall be equal to a variable in the infinite (changes in its absolute than any big is positive) Get a theorem about 0 "zero limits of variables， called an infinitesimal"
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