Question

tìm x biết 

a) \(x^2+5x=0\)

b)3x(x-1)=1-x

Answer 1

a)\(x^2+5x=0\Rightarrow x\left(x+5\right)\Rightarrow\left[{}\begin{matrix}x=0\\x+5=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)

b)\(3x\left(x-1\right)=1-x\Leftrightarrow3x^2-3x-1+x=0\Leftrightarrow3x\left(x-1\right)+\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(3x+1\right)=0\Rightarrow\left[{}\begin{matrix}x-1=0\\3x+1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=1\\x=-\dfrac{1}{3}\end{matrix}\right.\)