Question

Tìm x biết

Answer 1

\(\dfrac{-27}{x-1}=\dfrac{x-1}{-3}\\ -27.\left(-3\right)=\left(x-1\right).\left(x-1\right)\\ 81=\left(x-1\right)^2\\ TH1:\\ \left(-9\right)^2=\left(x-1\right)^2\\ x-1=-9\\ x=-9+1\\ x=-8\\ TH2:\\ 9^2=\left(x-1\right)^2=x-1=9\\ x=9+1\\ x=10\)