\(8x\left(x-3\right)-8\left(x-1\right)\left(x+1\right)=20\)
\(\Leftrightarrow8x^2-24x-8\left(x^2-1\right)=20\)
\(\Leftrightarrow8x^2-24x-8x^2+8=20\)
\(\Leftrightarrow\left(8x^2-8x^2\right)+\left(-24x+8\right)=20\)
\(\Leftrightarrow-24x=20-8\)
\(\Leftrightarrow-24x=12\)
\(\Leftrightarrow x=12:\left(-24\right)\)
\(\Leftrightarrow x=-\frac{1}{2}\)
Vậy: \(x=-\frac{1}{2}\)
\(8x\left(x-2\right)-8\left(x-1\right)\left(x+1\right)=20\)
\(\Leftrightarrow8x^2-24x-8\left(x^2-1\right)=20\)
\(\Leftrightarrow8x^2-24x-\left(8x^2-8\right)=20\)
\(\Leftrightarrow8x^2-24x-8x^2+8=20\)
\(\Leftrightarrow-24x+8=20\)
\(\Leftrightarrow-24x=20-8\)
\(\Leftrightarrow-24x=12\)
\(\Leftrightarrow x=-\frac{1}{2}\)
Ta có:
8x(x - 3) - 8(x - 1)(x + 1) = 20
=> 8x2 - 24x - 8(x2 - 1) = 20
=> 8x2 - 24x - 8x2 + 8 = 20
=> -24x = 12
=> x = 12/-24 = -2
cảm ơn các bạn các bạn giúp mình bài sắp đăng ạ :))))