Let f be a continuous function on the interval a,b. Suppose that for every cin[a,b]
and din[a,b] we know that int_c^d f(x)dx=0. Prove that f(x)=0 for all x.
6Let f be a continuous function on the interval [,b]. Suppose that for every c [,b] and d [,b] we know that Jc f()dx = 0. Prove that f() = 0 for all .