Vgln. eerste graad (reeks 3)

Reeks met haakjes

\(3(x+2)=9+(12+4x)\)

\(\begin{align} & \color{red}{3} (x+2)& = & 9 \color{red}{+} (12+4x) \\\Leftrightarrow & 3x+6& = &9+12+4x \\\Leftrightarrow & 3x \color{red}{+6} & = &21 \color{red}{+4x} \\\Leftrightarrow & 3x \color{red}{+6} \color{blue}{-6} \color{blue}{-4x} & = &21 \color{red}{+4x} \color{blue}{-4x} \color{blue}{-6} \\\Leftrightarrow & 3x-4x& = &21-6 \\\Leftrightarrow & -x& = &15 \\\Leftrightarrow & \frac{-x}{ \color{red}{-1} }& = &\frac{15}{ \color{red}{-1} } \\\Leftrightarrow & x = -15 & & \\ & V = \left\{ -15 \right\} & \\\end{align}\)