Download e-book for iPad: Functional Equations Electronic Edition 2007 by Titu Andreescu, Iurie Boreico

By Titu Andreescu, Iurie Boreico

Show description

Read Online or Download Functional Equations Electronic Edition 2007 PDF

Best nonfiction_4 books

Work, Earnings and Other Aspects of the Employment Relation - download pdf or read online

Quantity sixteen of "Research on financial" incorporates a number of 13 papers from the second one Biannual assembly of the Society for the examine of financial Inequality, Berlin, July, 2007. This convention brings jointly either validated students within the box of source of revenue distribution in addition to complicated graduate scholars and new Ph.

Read e-book online Molecular Structure by Diffraction Methods: v. 3 (Specialist PDF

Professional Periodical experiences offer systematic and special evaluate assurance of development within the significant components of chemical examine. Written by means of specialists of their expert fields the sequence creates a distinct provider for the energetic study chemist, delivering average serious in-depth bills of growth particularly components of chemistry.

Additional resources for Functional Equations Electronic Edition 2007

Sample text

2 2 y Let a = 1. Setting z = leads to x f (x + y) = f (x) + f (y) for any x = 0 and any y. The same remains true holds if x = 0. It follows now by (3)that f (xy) = f (x)f (y). √ Then f (x + y) = f (x) + (f ( y))2 ≥ f (x) for y ≥ 0. Hence f is an additive increasing function and therefore f (x) = f (1)x = x. So, f ≡ 2, f ≡ 0 or f (x) ≡ x. It clear that all the three functions satisfy (3). Exercises Problem 109. (Bulgaria, 1994) Find all functions f : R → R such that xf (x) − yf (y) = (x − y)f (x + y) for all x, y ∈ R.

Thus g(x − y) = ±(g(x)f (y) − g(y)f (x)). Suppose g(x − y) = −(g(x)f (y) − g(y)f (x)) for some x, y. Let A be the set of such (x, y) and B be the set of (x, y) for which g(x − y) = g(x)f (y) − g(y)f (x). Then A, B are closed and A B = R2 thus there is a point (u, v) which belongs to both A, B. Then g(u − v) = (g(u)f (v) − g(v)f (u)) = −(g(u)f (v) − g(v)f (u)) possible only when g(u − v) = 0. If we interchange x with y we get that f is even. If we set y → −y we get f (x+y) = f (x)f (y)+g(x)g(−y) and analogously f (x+ y) = f (x)f (y) + g(−x)g(y).

So u1 would be rational, impossible. So one of them, say 11 meets an infinite number 60 of times. As we have infinitely many zeroes and ones, the blocks 01 must also occur an infinite number of times. So if the l + 1th , l + 2th digits of u1 are 1 we get 34 < {2l u1 } < 1 but if l + 1th , l + 2th digits of 1 are 0 and 1 we have 14 < {2l u1 } < 12 . So {2l u1 } has infinitely many u members in the disjoint intervals [ 41 ; 12 ] and [ 34 ; 1] thus cannot converge. We derive an analogous contradiction if 00 meets infinitely many times.

Download PDF sample

Functional Equations Electronic Edition 2007 by Titu Andreescu, Iurie Boreico

by David

Rated 4.44 of 5 – based on 47 votes