Question

x^3-4x^2+x+6= 0 tìm nghiệm của đa thức

 

Answer 1

\(x^3-4x^2+x+6=0\)

\(\Leftrightarrow x^3-5x^2+6x+x^2-5x+6=0\)

\(\Leftrightarrow x\left(x^2-5x+6\right)+\left(x^2-5x+6\right)=0\)

\(\Leftrightarrow\left(x+1\right)\left(x^2-5x+6\right)=0\)

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

\(\Leftrightarrow\left[\begin{array}{nghiempt}x+1=0\\x-2=0\\x-3=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=-1\\x=2\\x=3\end{array}\right.\)