Question

Answer 1

\(d,\Leftrightarrow\left(x-1\right)^{9-7+1}=27^2\\ \Leftrightarrow\left(x-1\right)^3=3^6\\ \Leftrightarrow\left(x-1\right)^3=9^3\\ \Leftrightarrow x-1=9\Leftrightarrow x=10\)

Answer 2

\(\left(x-1\right)^9:\left(x-1\right)^7.\left(x-1\right)=27^2\)

\(\Rightarrow\left(x-1\right)^2.\left(x-1\right)=27^2\)

\(\Rightarrow\left(x-1\right)^3=729\)

\(\Rightarrow x-1=9\Rightarrow x=10\)

Answer 3

(x-1)⁹: (x-1)⁷.(x-1)=27²
(x-1)⁹:(x-1)⁸=729
x-1=729
x=730
vậy x=730