2. Let f be a continuous function defined on interval[a,b]. If  f (a) f (b) − f (a) − f (b) +1＜0 , then there exists a number c between a and b such that f(c) =1 .
(A)O
(B)X

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統計： A(0), B(1), C(0), D(0), E(0) #2348337