y = mx + b or f ( ) x = mx + b Graph is a line with point ( 0,b ) and slope m. a > 0 or down if a < 0 and has a vertex at ( h , k ) . Graph is a circle with radius ( h , k ) . Graph is an ellipse with center ( h , k ) with vertices a units right/left from the center and vertices b units up/down from the center.