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Real analysis : Measurable Functions

Q1. If 0<=a_1<=a_2<=a_3<=....,( 1,2,3 are the subscripts of a)
0<=b_1<=b_2<=b_3<=......(1,2,3 are the subscripts of b)
and a_n --> a and b_n -->b
Then prove that a_n*b_n -->a*b

Q2.Let f: R --> R be monotonically increasing, i.e.
f(x_1)<= f(x_2) for x_1< = x_2.
Show that f is measurable.
Hint: You may extend f to f':[-infinity,infinity]-->[-infinity,infinity]and
show that (x_alpha,infinity] is contained in f'^-1((alpha,infinity])
is contained in [x_alpha,infinity],where x_alpha=inf{x:f'(x)>alpha}

Please respond with Complete proof/solution.
NOTE: f' means a bar on the head of f

Solution Summary

Measurable functions are investigated. The solution is detailed and well-presented.