\(\left(2x+3\right)\left(x+2\right)^2\left(2x+5\right)=3\)
\(\Leftrightarrow4x^4+32x^3+95x^2+124x+57=0\)
\(\Leftrightarrow4x^4+4x^3+28^3+28x^2+67x^2+67x+57x+57=0\)
\(\Leftrightarrow4x^3\left(x+1\right)+28x^2\left(x+1\right)+67x\left(x+1\right)+57\left(x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(4x^3+28x^2+67x+57\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(4x^3+12x^2+16x^2+48x+19x+57\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(4x^2\left(x+3\right)+16x\left(x+3\right)+19\left(x+3\right)\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(x+3\right)\left(4x^2+16x+19\right)=0\)
\(\forall x\)ta có: \(4x^2+16x+19=4x^2+16x+16+3=\left(2x+4\right)^2+3\ge3>0\)
\(\Rightarrow\orbr{\begin{cases}x+1=0\\x+3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-1\\x=-3\end{cases}}}\)
Vậy tập nghiệm của pt là S={-1;-3}
