Question

Giải phương trình 2x^2-2x-4=0

Answer 1

\(2x^2-2x-4=2\left(x^2-x-2\right)=2\left(x-2\right)\left(x+1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x-2=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)

Answer 2

`2x^2-2x-4=0`

\(\Delta=\left(-2\right)^2-4.2.\left(-4\right)\)

   \(=4+32=36>0\)

`->` pt có 2 nghiệm

\(\left\{{}\begin{matrix}x_1=\dfrac{2+\sqrt{36}}{4}=2\\x_2=\dfrac{2-\sqrt{36}}{4}=-1\end{matrix}\right.\)