Question

tìm x

2x²+2x-0,8=-4/5

Answer 1

`2x^2 + 2x - 0,8 = -4/5`

`<=> 2x^2 + 2x = -4/5 + 0,8`

`<=> 2x(x+1) = 0`

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

Answer 2

2x² + 2x - 0,8 = - 4/5

=> 2x² + 2x = - 4/5 + 0,8

=> 2x(x + 1) = 0

=> 2x = 0     <=> x = 0

=> x + 1 = 0    <=> x = - 1

vậy x = [0 , - 1]

Answer 3

\(2x^2+2x-0,8=-\dfrac{4}{5}\)

`=>` \(2x\left(x+1\right)=-\dfrac{4}{5}+0,8\)

`=>2x(x+1)=0`

`=>`\(\left[{}\begin{matrix}2x=0\\x+1=0\end{matrix}\right.\)`<=>` \(\left[{}\begin{matrix}x=0:2\\x=0-1\end{matrix}\right.\)`<=>` \(\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)