Question

tìm x biết: a.x( x+5) =0

b. (2x-6)(-4x-8)=0

Answer 1

làm ăn vầy là chết tui rồi

\(x.\left(x+5\right)=0\)

\(\Leftrightarrow\)\(x=0\Rightarrow x=0\)

\(\Leftrightarrow\)\(x+5=0\Rightarrow x=-5\)

Vậy \(x\in\left\{0;-5\right\}\)

b) \(\left(2x-6\right)\left(-4x-8\right)\)

\(\Leftrightarrow\)\(2x-6=0\Rightarrow x=\frac{6}{2}=3\)

\(\Leftrightarrow\)\(-4x-8=0\Rightarrow x=-2\)

Vậy \(x\in\left\{3;-2\right\}\)

Answer 2

a) x . ( x + 5 ) = 0

\(\Rightarrow\orbr{\begin{cases}x=0\\x+5=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)

b) ( 2x - 6 ) . ( -4x - 8 ) = 0

\(\Rightarrow\orbr{\begin{cases}2x-6=0\\-4x-8=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x=6\\-4x=8\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=3\\x=-2\end{cases}}\)

Answer 3

\(x( x+5) =0 \)

\(\Rightarrow\orbr{\begin{cases}x=0\\x+5=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)

vậy_____

\( (2x-6)(-4x-8)=0\)

\(\Rightarrow\orbr{\begin{cases}2x-6=0\\-4x-8=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=3\\x=-2\end{cases}}\)

vậy_____

Answer 4

\(\Rightarrow\orbr{\begin{cases}x=0\\x+5=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=-5\end{cases}}\)

Vậy \(x=0\)hoặc\(x=-5\)

b.\(\Rightarrow\orbr{\begin{cases}2x-6=0\\-4x-8=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=-2\end{cases}}\)

Vậy x=3 hoặc x=-2