\(8x\left(x-3\right)-8\left(x-1\right)\left(x+1\right)=20\)
\(\Leftrightarrow8x^2-24x-8\left(x^2-1\right)=20\)
\(\Leftrightarrow8x^2-24x-8x^2+8=20\)
\(\Leftrightarrow-24x=12\)
\(\Leftrightarrow x=-0,5\)
Giải:
\(8x\left(x-3\right)-8\left(x-1\right)\left(x+1\right)=20\)
\(\Leftrightarrow8x^2-24x-8\left(x^2-1\right)=20\)
\(\Leftrightarrow8x^2-24x-\left(8x^2-8\right)=20\)
\(\Leftrightarrow8x^2-24x-8x^2+8=20\)
\(\Leftrightarrow-24x+8=20\)
\(\Leftrightarrow-24x=12\)
\(\Leftrightarrow x=-\dfrac{1}{2}\)
Vậy ...
\(8x\left(x-3\right)-8\left(x-1\right)\left(x+1\right)=20\)
\(\Leftrightarrow8x^2-24x-8\left(x^2-1\right)=20\)
\(\Leftrightarrow8x^2-24x-8x^2+8=20\)
\(\Leftrightarrow-24x=12\)
\(\Leftrightarrow x=-0,5\).
\(8x\left(x-3\right)-8\left(x-1\right)\left(x+1\right)=20\)
\(\Leftrightarrow8x^2-24x-\left(8x-8\right)\left(x+1\right)=20\)
\(\Leftrightarrow8x^2-24x-8x^2-8x+8x+8=20\)
\(\Leftrightarrow-24x=12\)
\(\Leftrightarrow x=-\dfrac{1}{2}\)
Vậy \(S=\left\{-\dfrac{1}{2}\right\}\)