\(\text{a},x=0ho\text{a}cx-7=0\\ x=0;x=7\\ b,x=0ho\text{a}cx+11=0\\ x=0;x=-11\\ c,\left(-25\right).\left(-3\right)=75\\ d,\left(-30\right).\left(-5\right)=150\)
`x.(x-7)=0`
`=> x = 0` hoặc `x - 7=0`
`=> x =0 ` hoặc `x = 7`
Vậy `x = {0;7}`
_________________________________
`x.(x+11)=0`
`=> x = 0` hoặc `x + 11=0`
`=> x = 0` hoặc `x = - 11`
Vậy `x = {0;11}`
______________________________
`(-25).(-3) = 75`
`(-30).(-5) = 150`
\(x(x-7)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=7\end{matrix}\right.\)
\(-------------------\)
\(x(x+11)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+11=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-11\end{matrix}\right.\)
\(-------------------\)
\((-25).(-3)=75\)
\((-30).(-5)= 150\)
