Ta có :
\(-12+3\left(-x+7\right)=-18\)
\(\Leftrightarrow\)\(-3x+21=-18+12\)
\(\Leftrightarrow\)\(-3x=-6-21\)
\(\Leftrightarrow\)\(-3x=-27\)
\(\Leftrightarrow\)\(x=\frac{-27}{-3}\)
\(\Leftrightarrow\)\(x=9\)
Vậy \(x=9\)
-12+3(-x+7)=-18
\(\Rightarrow3\left(x+7\right)=-18-\left(-12\right)\)
\(\Rightarrow3\left(x+7\right)=-6\)
\(\Rightarrow x+7=-6:3\)
\(\Rightarrow x+7=-2\)
\(\Rightarrow x=-2-7\)
\(\Rightarrow x=-9\)
Vậy x=-9
\(-12+3\left(-x+7\right)=-18\)
\(3\left(-x+7\right)=-18+12\)
\(-3x+21=-6\)
\(-3x=-6-21\)
\(-3x=-27\)
\(x=-27:\left(-3\right)\)
\(x=9\)
- 12 + 3.( - x + 7 ) = - 18
- 12 + ( - 3x ) + 21 = - 18
- 3x = - 18 - ( - 12 ) - 21
- 3x = - 27
x = -27 : ( - 3 )
x = 9