b.
ĐKXĐ: \(x>\frac{11}{2}\)
\(\Leftrightarrow log\frac{x-1}{2x-11}=log2\)
\(\Leftrightarrow\frac{x-1}{2x-11}=2\)
\(\Leftrightarrow x=7\)
c.
ĐKXĐ: \(x>5\)
\(log_2\left(x-5\right)\left(x+2\right)=3\)
\(\Leftrightarrow\left(x-5\right)\left(x+2\right)=8\)
\(\Leftrightarrow x^2-3x-18=0\)
\(\Leftrightarrow x=6\)
c. ĐKXĐ: \(x>3+\sqrt{2}\)
\(\Leftrightarrow x^2-6x+7=x-3\)
\(\Leftrightarrow x^2-7x+10=0\)
\(\Leftrightarrow x=5\)