Question

(x+5) . (x-4) = 0

(x-1) . (x-3)=0

(3-x)-(x-3)=0

x. (x+1)=0

Answer 1

X=4

Answer 2

\(a,\left(x+5\right)\left(x-4\right)=0.\)

\(\Leftrightarrow\left[{}\begin{matrix}x+5=0.\\x-4=0.\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-5.\\x=4.\end{matrix}\right.\)

Vậy..........

\(b,\left(x-1\right)\left(x-3\right)=0.\)

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

\(\Leftrightarrow\left[{}\begin{matrix}x=1.\\x=3.\end{matrix}\right.\)

Vậy..........

\(c,\) Sửa đề:

\(\left(3-x\right)\left(x-3\right)=0.\)

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

\(\Leftrightarrow x=3.\)

Vậy..........

\(d,x\left(x+1\right)=0.\)

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

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

Vậy..........

Answer 3

(3 - \(x\)) - (\(x-3\)) = 0

3 - \(x\) - \(x\) + 3 = 0

(3 + 3) - (\(x+x\)) = 0

     6 - 2\(x\) = 0

        2\(x\) = 6

        \(x\) = 6 : 2

        \(x\) = 3

Vậy \(x\) = 3