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Since for some . But


vanishes also for and . Thus, in view of the fact that has five distinct zeros in the closed interval , the fifth derivative has at least one zero in , the fifth derivative has at least one zero in . We easily find

and thus have, for some 

But, by the continuity of it follows as before that

for some between and . Inserting this value in (7.31), (7.29) follows: |