Using only math symbols (no functions like sin, cos, log, etc.) create an expression with only two 2s equal to 5 (no other digits or constants).

The most basic meaning of an operation like + is that it is a function with domain the set of all pairs (x,y) of real numbers and range the set of real numbers.  This is correct, but,
relatively speaking, a recently formulated way of looking at the operation of +, which has deep historical roots.  Moreover, one would not want, I think, to start young kids thinking
about + as a function.  Rather, it is an "operation" on a pair of numbers.

Certainly, sqrt is a function.  Sticking witht the reals for simplicity, sqrt is a function from the non-negative reals to the non-negative reals.

The function, formally, is a set f of ordered pairs in A cross B, where A and B are sets.  f is the name for the set.

Please write back if my comments are not clear, are not relevant, or, worst of all,  if I've made a mistake.

- Doctor Jerry, The Math Forum
  <http://mathforum.org/dr.math/>

Posted by pcbouhid on 2005-10-15 14:55:46