x^2(2x+1)-4(2x+1)
=(x^2-4)(2x+1)
R bn cho 2 cái đấy =0 từ đó tính đc mỗi cái
X có 2 gtri nha
Tự lm nốt
Ta có :
\(2x^3+x^2-8x-4=0\)
\(\Leftrightarrow\left(2x^3+4x^2\right)-\left(3x^2+6x\right)-\left(2x+4\right)=0\)
\(\Leftrightarrow2x^2\left(x+2\right)-3x\left(x+2\right)-2\left(x+2\right)=0\)
\(\Leftrightarrow\left(x+2\right)\left(2x^2-3x-2\right)=0\)
\(\Leftrightarrow\left(x+2\right)\left[\left(2x^2+x\right)-\left(4x+2\right)\right]=0\)
\(\Leftrightarrow\left(x+2\right)\left[x\left(2x+1\right)-2\left(2x+1\right)\right]=0\)
\(\Leftrightarrow\left(x+2\right)\left(x-2\right)\left(2x+1\right)=0\)
Ta có các trường hợp :
* \(x+2=0\Leftrightarrow x=-2\)
* \(x-2=0\Leftrightarrow x=2\)
* \(2x+1=0\Leftrightarrow x=-\frac{1}{2}\)
Vậy .....
