For each of the following functions F, determine whether or not F is a valid cumulative distribution function, i.e., whether or not F satisfies properties (a) through (d) of Theorem 2.5.2.

a) 1,)( RxxxF  cannot be a CDF for many reasons, including the facts
that it is negative for x<0 and that 

)(lim xF
x
(should be 1!).
b)









1,1
10,
0,0
)(
x
xx
x
xF is a valid CDF. It´s defined for all real numbers,
right-continuous, monotonically non-decreasing, never negative,
approaches 0 to the left and 1 to the right. Actually, it´s easy to see the
uniform PMF ]1,0[,1)(  xxf (0 otherwise).
c)...