Question

Tìm x

a) 5x(x-1)-3x(x-1)=0

b) 2x²(x+3)-2x-6=0

Answer 1

a. \(5x\left(x-1\right)-3x\left(x-1\right)=0\\ \Leftrightarrow\left(5x-3x\right)\left(x-1\right)=0\\ \Leftrightarrow\left\{{}\begin{matrix}2x=0\\x-1=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)

b. \(2x^2\left(x+3\right)-2x-6=0\\ \Leftrightarrow2x^2\left(x+3\right)-2\left(x+3\right)=0\\ \Leftrightarrow\left(2x^2-2\right)\left(x+3\right)=0\\ \Leftrightarrow2\left(x^2-1\right)\\ \Leftrightarrow\left\{{}\begin{matrix}2=0\left(vô.lí\right)\\x+3=0\\x^2-1=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=-3\\x=\pm1\end{matrix}\right.\)