prove that if f'(x)>0 for each x in the interval I ,(where I=(a,b),
(a,b], [a,b),(-infinity ,b),(-infinity,b],(a,+infinity),[a,+infinity)
and R=(-infinity, +infinity)) then 'f' is increasing( where 'f' is
increasing means if x,y belongs to Domain of f, x<y then f(x)<f(y)) on
I.
please give me the detailed proof