Question

Tìm x, biết:

x⁴+4x³-16x-16=0

Giúp mình với chiề mai mình nộp rồi

 

Answer 1

\(x^4+4x^3-16x-16=0\)

\(\Leftrightarrow\left(x^4-16\right)+\left(4x^3-16x\right)=0\)

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

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

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

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

\(\Leftrightarrow\hept{\begin{cases}x-2=0\\\left(x+2\right)^3=0\end{cases}\Leftrightarrow\hept{\begin{cases}x=2\\x=-2\end{cases}}}\)

=.= hok tốt!!