Cho log26...

Câu hỏi: Cho log₂6 = a và log₃5 = b  . Hãy tính ${\log }_{12}\left(\sqrt{20}\right)$ theo a,b.

A.. ${\log }_{12}\left(\sqrt{20}\right)=\frac{ab-b+2}{2(a+1)}$

B. ${\log }_{12}\left(\sqrt{20}\right)=\frac{ab+b-2}{2(a+1)}$

C. ${\log }_{12}\left(\sqrt{20}\right)=\frac{ab+b-2}{2(a-1)}$

D. ${\log }_{12}\left(\sqrt{20}\right)=\frac{ab-b+2}{2(a-1)}$