\(2 . (x - 1) - 7 = 9\)
\(2 . (x - 1) =9+7\)
\(2.(x-1)=16\)
\(x-1=16:2\)
\(x-1=8\)
\(x=8+1\)
\(x=9\)
\(2.\left(x-1\right)-7=9\)
\(\Rightarrow2.\left(x-1\right)=9+7\)
\(\Rightarrow2.\left(x-1\right)=16\)
\(\Rightarrow x-1=8\)
\(\Rightarrow x=9\)
\(2\times\left(x-1\right)-7=9\)
\(\Leftrightarrow2x-2-7=9\)
\(\Leftrightarrow2x=18\)
\(\Leftrightarrow x=9\)
\(2\left(x-1\right)-7=9\)
\(2\left(x-1\right)=16\)
\(x-1=8\)
\(x=9\)
=> \(2x^2-2x=9+7=16\)
=> \(2x^2-2x-16=0\)
\(\Delta=\left(-2\right)^2-4.2.-16=132>0\)
=> pt có 2 nghiệm pt
\(x_1=\dfrac{2+\sqrt{132}}{4};x_2=\dfrac{2-\sqrt{132}}{4}\)
