Question

Tìm x biết

x/3+x^2/2=0

(x^2+3)(x+1)+x=-1

Answer 1

\(\frac{x}{3}+\frac{x^2}{2}=0\)

\(\Leftrightarrow\frac{2x+3x^2}{6}=0\Leftrightarrow3x^2+2x=0\)

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

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

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

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

Mà \(x^2+4>0\)nên \(x+1=0\Leftrightarrow x=-1\)