TeX Quellcode:

\begin{array}{crcrcl} \text{I} & 4a+2b &=& 0 \cr \text{II} & a+b &=& 1 &\vert& -b \cr \cr \text{I} & 4a+2b &=& 0 \cr \text{II} & a &=& 1-b \cr \cr \text{II in I} & 4(1-b)+2b &=& 0 \cr & 4-4b+2b &=& 0 \cr & 4-2b &=& 0 &\vert& -4 \cr & -2b &=& -4 &\vert& :\left(-2\right) \cr & b &=& 2 \cr \cr \text{b in II} & a &=& 1-2 \cr & a &=& -1 \end{array}