Question

Giải phương trình

(4x+1)(12x-1)(3x+2)(x+1)=4

 

Answer 1

\(\Leftrightarrow\left(4x+1\right)\left(3x+2\right)\left(12x-1\right)\left(x+1\right)-4=0\)

\(\Leftrightarrow\left(12x^2+11x+2\right)\left(12x^2+11x-1\right)-4=0\)

Đặt \(12x^2+11x-1=t\)

\(\Rightarrow\left(t+3\right)t-4=0\Leftrightarrow t^2+3t-4=0\Rightarrow\left[{}\begin{matrix}t=1\\t=-4\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}12x^2+11x-1=1\\12x^2+11x-1=-4\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}12x^2+11x-2=0\\12x^2+11x+3=0\end{matrix}\right.\)

\(\Leftrightarrow...\)