# How do I use Cramer's rule to solve a 2xx2 matrix?

Cramer's rule is used to solve a square system of linear equations, that is, a linear system with the same number of equations as variables. In a square system, you would have an $n \times \left(n + 1\right)$ matrix.
So you should have a $2 \times 3$ matrix in order to use Cramer's rule. A $2 \times 2$ matrix would only have the coefficients of the variables; you need to include the constants of the equations.