Question

tìm x ,biết [ 2 phần 3 x - 1] tất cả mũ 2 = 25

 

Answer 1

\(\left(\frac{2}{3}x-1\right)^2=25\)

\(\Rightarrow\left(\frac{2}{3}x-1\right)^2=5^2=\left(-5\right)^2\)

\(TH1:\frac{2}{3}x-1=5\)

           \(\frac{2}{3}x=5+1=6\)

           \(x=6:\frac{2}{3}=6.\frac{3}{2}=9\)

\(TH2:\frac{2}{3}x-1=-5\)

            \(\frac{2}{3}x=-5+1=-4\)

             \(x=-4:\frac{2}{3}=-4.\frac{3}{2}=-6\)

Vậy: \(x\in\left\{-6;9\right\}\)