Question

giải pt 

\(12x^3-115x^2+53x+90=0\)

Answer 1

\(\Leftrightarrow12x^3-108x^2-7x^2+63x-10x+90=0\\ \Leftrightarrow\left(x-9\right)\left(12x^2-7x-10\right)=0\\ \Leftrightarrow\left(x-9\right)\left(12x^2-15x+8x-10\right)=0\\ \Leftrightarrow\left(x-9\right)\left(4x-5\right)\left(3x+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=9\\x=\dfrac{5}{4}\\x=-\dfrac{2}{3}\end{matrix}\right.\)

Answer 2

\(\Leftrightarrow\left(x-9\right)\left(4x-5\right)\left(3x+2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=9\\x=\dfrac{5}{4}\\x=-\dfrac{2}{3}\end{matrix}\right.\)