## Simultaneous equations (linear)
-- Unique solution - lines intersect at point
-- Infinitely many solutions - lines are equal
-- No solution - lines are parallel
+- **Unique solution** - lines intersect at point
+- **Infinitely many solutions** - lines are equal
+- **No solution** - lines are parallel
Solving in matrix form - use inverse $A^{-1}= {1 \over {ad-bc}}\begin{bmatrix}d & -b \\ -c & a\end{bmatrix}$. $A^{-1}$ exists for infinite solutions or no solutions ($ad-bc=0$), does not exist for unique solutions ($ad-bc \ne 0$).
-Or use `det` on CAS.
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+Or use Matrix -> `det` on CAS.
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