



 
Hi Adam, This is a place where problems arise from some numbers having two decimal expansions. It is possible to make 0.1 according to the rule you describe. Take x = 0.09999999... and y = 0.999999.... You get f(x,y) = 0.0999... = 0.1. In cases like this, it is often best to work with the nonterminating decimal expansion. This is the one that ends in the infinite sequence of nine's. You might have trouble finding x and y so that f(x,y) = 0.010101010101010... Notice that this has no nines. Perhaps it is zeros that require some care? Victoria  


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