Ta có : 2x3+ 7x2+7x+2 =0
<=> \(2\left(x^3+1\right)+7x\left(x+1\right)=0\)
<=> \(2\left(x+1\right)\left(x^2-x+1\right)+7x\left(x+1\right)=0\)
<=> \(\left(x+1\right)\left(2x^2-2x+2+7x\right)=0\)
<=> \(\left(x+1\right)\left(2x^2+5x+2\right)=0\)
<=> \(\left(x+1\right)\left(2x+1\right)\left(x+2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=-1\\x=-0,5\\x=-2\end{matrix}\right.\)
2x3+7x2+7x+2=0=>2(x3+1)+7x(x+1)=0
=>2(x+1)(x2-x+1)+7x(x+1)=0
=>(x+1)(2x2-2x+2+7x)=0
=> x = -1 hoặc 2x2+5x+2=0
=>2x2+4x+x+2=0
=>2x(x+2)+(x+2)=0
=>(x+2)(2x+1)=0
=>x=-1 hoặc x=-2 hoặc x=\(\dfrac{-1}{2}\)
