Vertex Form of a Parabola Objective: identify the vertex of a parabola using its equation; change from vertex form to standard form and standard form to vertex form. How are transformation rules used to find the vertex of a parabola? Why do we need “completing the square”?
Standard Form of a Quadratic
General Form of a Quadratic Stretch Up/Down Left/Right
Vertex The highest or lowest point on a parabola
Parent: f(x) = x2 Vertex: (o,o)
Child: f(x) = 2(x+3)2 - 1 Stretched vertically by 2, left 3, down 1 Vertex: _______
“a” is from the standard equation Vertex Form (h, k) is the vertex “a” is from the standard equation
Ex 1) Identify the vertex
Ex 2) Identify the vertex
Ex 3) Write the vertex form of the equation with vertex: (3, 6) a = 2
Ex 4) Write the vertex form of the equation with vertex: (-8, 2) a = 3
Ex 5) Find “a” if the vertex is (2, 5) and the graph goes through the point (4, 3)
Ex 6) Find “a” if the vertex is (-3, 1) and the graph goes through the point (-2, 8)
Changing Vertex Form to Standard Form 1. Box it Out (or FOIL) 2. Distribute 3. Combined like terms
Ex 1) Re-write the equation in standard form
Ex 2) Re-write the equation in standard form
Changing Standard Form to Vertex From 1. Move the constant term over 2. Complete the Square 3. Add the same about to the left side 4. Factor 5. Move the constant term back over
Ex 1) Change to vertex form
Ex 2) Change to vertex form
Ex 3) Change to vertex form