Recall that a set B is dense in R if an clement of B can be

Recall that a set B is dense in R if an clement of B can be found between any two real numbers a

Solution

a) rational numbers p/q and q<10 it is dense in r because the highest number of this set will be less then the R

and also the lowest number will be bigger then the lesser number in R. hence it is dense.

b) this will be dense again for the same reason

c) this will not be dense because we find find the lesser then the lowest number of this set but the bigger values will all equal to R. hence not dense,