## 7.2 Simultaneous Linear Equations of More Variables

#### Simultaneous Linear Equations of Three Variables

- Consider a literal simultaneous linear equations with three variables:

\begin{cases}a_{1} x+b_{1} y+c_{1} z=d_{1} \\a_{2} x+b_{2} y+c_{2} z=d_{2} \\a_{3} x+b_{3} y+c_{3} z=d_{3}\end{cases}

The methods and skills involved are still the same as with two variables, namely elimination and substitution.

- It is also possible to solve such linear systems with the help of a calculator nowadays. Nevertheless, sometimes it might be quicker to solve it by hand if you realise variables can be cancelled out very quickly.

- To interpret it geometrically, the equation a x+b y+c z=d actually represents a plane in the 3-D space. Thus, solving the three simultaneous equations is actually same as finding the intersection point/line/plane of the 3 planes, if any.