Cho \({\log _2}3 = a;{\log _5}4 = b;{\log _3}7 = c...

Câu hỏi: Cho \({\log _2}3 = a;{\log _5}4 = b;{\log _3}7 = c\). Tính  \({\log _9}175\) theo a,b,c?

A. \(\frac{2}{a} + \frac{2}{b} + \frac{2}{c}\)

B. \(\frac{{a + b + c}}{2}\)

C. \(\frac{2}{{a + b}} + \frac{c}{2}\)

D. \(\frac{2}{{ab}} + \frac{c}{2}\)