SAT Problem of the Day

5.5 The Quadratic Formula 5.5 The Quadratic Formula Objectives: Use the quadratic formula to find real roots of quadratic equations Use the roots of a quadratic equation to locate the axis of symmetry of a parabola

The Quadratic Formula If ax 2 + bx + c = 0 and a = 0, then the solutions, or roots, are

Example 1 olve x 2 – 16x – 36 = 0.Use the quadratic formula to s S a = b = c = x = 18 or -2

Example 2 Use the quadratic formula to solve 5x = 7x. Give exact solutions and approximate solutions to the nearest tenth. a = b = c =5-71 5x 2 – 7x + 1 = 0

Practice Use the quadratic formula to solve 2x 2 – 6x = -3. Give exact solutions and approximate solutions to the nearest tenth.

Axis of Symmetry of a Parabola If y = ax 2 + bx + c, where a = 0, then the equation for the axis of symmetry of the parabola is

Example 3 Let f(x) = -2x x 2. Write an equation for the axis of symmetry of the graph, and find the coordinates of the vertex. the axis of symmetry is f(x) =-2x+ 32x 2

Example 3 Let f(x) = -2x x 2. Write an equation for the axis of symmetry of the graph, and find the coordinates of the vertex. the axis of symmetry is the coordinates of the vertex are

Practice Let f(x) = x 2 – 4x + 1. Write an equation for the axis of symmetry of the graph, and find the coordinates of the vertex.

Homework Lesson 5.5 exercises ALT odds, ALL.