9. 若\( 4x+2 \)為7與13的等差中項,則x=?
(A)4
(B)3
(C)2
(D)1
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統計: A(0), B(0), C(1), D(0), E(0) #3873697
統計: A(0), B(0), C(1), D(0), E(0) #3873697