110 likes | 210 Views
9.8 Using the Discriminant. Objective: SWBAT use the quadratic formula to determine if the graph of a quadratic function will intersect the x-axis in zero, one, or two points. Mini Quiz 29. 1. Solve 2 x 2 – 3 x – 2 = 0 2. Graph y = - x 2 – 2 x + 1. Quick Review.
E N D
9.8 Using the Discriminant Objective: SWBAT use the quadratic formula to determine if the graph of a quadratic function will intersect the x-axis in zero, one, or two points.
Mini Quiz 29 1. Solve 2x2 – 3x – 2 = 0 2. Graph y = -x2 – 2x + 1
Quick Review 1. What is the Vertex and Axis of Symmetryformula? 2. What is the Quadratic Formula?
Overview Methods in Solving Quadratic Equations: Graphing Square Roots Factoring ( )( ) = 0 Completing the Square ( )2 Quadratic Formula Discriminant b2 - 4ac
Discrimin… Discriminate – to note or observe a difference (according to www.dictionary.com ) Discriminant - a relatively simple expression that determines ... the nature of the roots, of a given equation or function (according to www.dictionary.com) Tells you the different number of times the graph crosses the x-axis (according to Ms. Ly in “plain Math English”) ???
The Amazing Discriminant! How can you tell the numbers of solutions (roots, x-intercepts) without graphing the quadratic function? Use the Discriminant!!!
How does it work? (negative)…no solution (zero)…1 solution (positive)…2 solutions
Practicing with the Discriminant Find the number of solution(s) the quadratic function/equation has. 1. 0 = x2 + x + 1 2. y = x2 + 2x – 2 3. y = 2x2 + 4x + 4. -3x2 + 5x – 1 = 0 5. 23x2 – 2x = -5 Discriminant: b2 – 4ac Zero Two One Two Zero
Wrap Up Discriminant • Discriminant b2 - 4ac • Tell you the number of solutions • – 0 • 0 1 • + 2 HW: P. 472 #1-9 all, 55-67 odd DLUQ: What does the discriminant tell you?