Question

giúp em cách làm với ạ

 

Answer 1

1) \(2\left(x-9\right)=12\Rightarrow x-9=12:2=6\)

\(\Rightarrow x=6+9=15\)

2) \(5x\left(x-3\right)-2\left(x-3\right)=0\)

\(\Rightarrow\left(x-3\right)\left(5x-2\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{2}{5}\end{matrix}\right.\)

3) \(\left(x-4\right)\left(7x-2\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=4\\x=\dfrac{2}{7}\end{matrix}\right.\)

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

\(\Rightarrow x^2-1-x^2-3x=0\Rightarrow3x=-1\Rightarrow x=-\dfrac{1}{3}\)