Nếu ${\log 7}x = 8{\log 7}a{b^2} - 2{\log 7}{a^3}b\ left( {a,b

"> "> Nếu ${\log 7}x = 8{\log 7}a{b^2} - 2{\log 7}{a^3}b\ left( {a,b > 0} \right)$ thì $x$ bằng: