SWBAT… solve quadratic equations Tues, 2/7

Agenda

1. Warm-up (15 min)

2. Solving quadratic equations (10 min)

3. Graphing calculator activity (10 min)

4. 4 additional problems (10 min)

Warm-Up: Factor each expression:

1. x2 + 11x + 18

2. p2 – 10pq + 16q2

3. n6 + n3 – 56 HW#6: Quadratic Equations: x2 + bx + c

Steps to solve quadratic equations: 1.) Set equation = 02.) Factor the equation 3.) Set each factor = 0 4.) Solve each variable5.) Check both solutions

Example: x2 + 11x = -18 1.) x2 + 11x + 18 = 02.) (x + 2)(x + 9) = 03.) x + 2 = 0 or x + 9 = 04.) x = -2 or x = -9

CHECK: Plug both answers into original equation x2 + 11x = -18 or x2 + 11x = -18

(-2)2 + 11(-2) = -18 (-9)2 + 11(-9) = -18

4 – 22 = -18 81 – 99 = -18

-18 = -18 -18 = -18

On your graphing calculator graph x2 + 11x + 18 You will need to change the “window”

x-min = -15 y-max = 15 y-min = -15 y-max = 15

What conclusion can you make about the solutions of a quadratic and it’s graph? The solutions of a quadratic equation is where the parabola crosses the

x-axis.

The solutions of a quadratic may also be called roots, zeros or x-intercepts.

Solve each equation:

1. -42 + m2 – m = 0

2. c2 = 3c

3. Find all the values of k: x2 + kx – 19

4. A rectangle has an area represented by x2 – 4x – 12 feet2. If the length is x + 2 feet, what is the width of the rectangle?