extended summary < Korrekturlesen < Englisch < Sprachen < Vorhilfe
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(Frage) überfällig  | | Datum: | 18:22 Di 26.05.2009 | | Autor: | az118 |
Hallo, habe nochmal einen Text zum überfliegen, wär nett.danke
The article deals with functions. The author explain that the image of x under f is define a funczion, which may be written as f(x). He informs about the importance of a graph of a function f. So, the graph is the set of all pairs (x,f(x)) in a cartesian coordinate system. The concept of the image can be extended from the image of a point to the image of a set. So if A is a subset of the domain, then f(A) is the subset of the range. It is called that f(A) is the image of A under f. An another point is the inverse image. For example, the preimage of (4,9) under the squaring function is the set (-3,3,-2,2). The author explains three important kinds of functions. The first is the injection, which states if f(a)=f(b) then a must equal b. The second kind is the surjection, which means that for every y in the codomain there is an x in the domain such that f(x)=y. At last, the bijection, which combines both. A function composition can be calculate like a illustration from g of f. The inverse of a function is the inverse relation of every function f. S o the inverse of the graph G=((1,5),(2,4)) is G^-1=((5,1),(4,2)). The author tells that on can not work with every function like this, because it is sometimes difficult or impossible to find the inverses. The specifying of a function can be different. So a function can be defined by tabulating, by a formula or an algorithm. Furthermore there are other ways of defining functions, like algebraic or analytic closure, limits, infinite series and so on.
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(Mitteilung) Reaktion unnötig  | | Datum: | 19:20 Do 28.05.2009 | | Autor: | matux |
$MATUXTEXT(ueberfaellige_frage)
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