Question

(x-9)(x+1)=0

Answer 1

`(x-9)(x+1)=0`

`<=>` $\left[\begin{matrix} x-9=0\\ x+1=0\end{matrix}\right.$

`<=>` $\left[\begin{matrix} x=9\\ x=-1\end{matrix}\right.$

Vậy `S={9;-1}`

Answer 2

`(x-9)(x+1)=0`

\(\Leftrightarrow\left[{}\begin{matrix}x-9=0\\x+1=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=9\\x=-1\end{matrix}\right.\)

vậy : `S={9;-1}`

Answer 3

=>x-9=0 hoặc x+1=0

=>x=9 hoặc x=-1

Answer 4

`-> x- 9 = 0` hoặc `x + 1 = 0`

`=> x = 9` hoặc `x = -1`