1) Graphs of first degree equations of the form Ax + By = C are straight lines. There are two cases: if B ≠ 0, the graph is of the form y = mx + b, and if B = 0 the graph is a vertical line.
2) Graphs of second degree equations of the form Ax2 + By2 + Cx + Dy = E are conic sections. The four types are circles, ellipses, parabolas, and hyperbolas.
3) Conic sections are the shapes that result from slicing a cone at different angles, such as a circle from a horizontal cut or an ellipse from an angled cut.