8-6 Solving Quadratic Equations using Factoring Goal: Solve quadratic equation by factoring the trinomial. Eligible Content: A1.1.1.5.2

To solve equations by factoring: Make sure equation ends with = zero. Factor the trinomial. Set each linear binomial equal to zero and solve for each variable.

Solve: x2 – 3x – 10 = 0 (x – 5)(x + 2) = 0 x – 5 = 0 x + 2 = 0 +5 +5 5 * 2 = 10 5 - 2 = 3 +5 +5 -2 -2 x = 5 or x = -2

Examples x2 – 9x + 14 = 0 x2 + 15x + 50 = 0 x2 + 3x = 54 x2 + 51 = 20x x = 2 or x = 7 x = -5 or x = -10 x = -9 or x = 6 x = 3 or x = 17 x = 8 or x = -1

Solve x2 – x – 20 = 0. Check your solution. A. {–5, 4} B. {5, 4} C. {5, –4} D. {–5, –4}

Practice Worksheet – “8-6 Solving Quadratic Equations by Factoring”

Remember: The solutions are the x-intercepts of the graph. We can check an answer by graphing it and finding x-intercepts.

Look at Graphs! Let’s look at problems from worksheet again.

Homework Page 507 #20-29