Question

tìm x

8x(x-3)-8(x-1)(x+1)=20
cảm ơn ạ! =))

Answer 1

8x(x - 3) - 8(x - 1)(x + 1) = 20

=> 8x² - 24x - 8(x² - 1) - 20 = 0

=> 8x² - 24x - 8x² + 8 - 20 = 0

=> -24x = -12

=> x = 1/2

Answer 2

\(8x\left(x-3\right)-8\left(x-1\right)\left(x+1\right)=20\Leftrightarrow8x^2-24x-8\left(x^2-1\right)=20\)

\(\Leftrightarrow8x^2-24x-8x^2+8-20=0\Leftrightarrow-24x-12=0\Leftrightarrow-24x=12\Leftrightarrow x=\frac{12}{-24}=\frac{-1}{2}\)

Answer 3

Ngọc Vĩ:Bạn sai rồi.-24x=12 mới đúng nhé!

Answer 4

Sửa lại: -24x = 12 => x = -1/2

Answer 5

\(8x\left(x-3\right)-8\left(x-1\right)\left(x+1\right)=20\)

=> \(8x^2-24x-8\left(x^2-1\right)=20\)

=> \(8x^2-24x-8x^2+8=20\)

=> \(-24x=-12\)

=> \(x=\frac{1}{2}\)

Answer 6

8x(x-3)-8(x-1)(x+1)=20
<=> 8x²-24x-8(x²-1)=20
<=> 8x²-24x-8x²+8=20
<=> -24x+8=20
<=>-24x=20-8
<=>-24x=12
<=>x=12:-24
<=>x=-0,5