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Quadratic Functions

Prep for Graphing Quadratic Functions


    1. [latex]\begin{array}{lc}B&\left(0,1\right)\\F&1\\C\;or\;D\;\;&x=1\\C\;or\;D&x=1\\A&\left(1,0\right)\\E&y=1\end{array}[/latex]

    1. [latex]y=3[/latex]
    2. [latex]x=3[/latex]
    3. [latex](-3,0)[/latex]

    1. Explain
    2. [latex]-4[/latex]
    3. [latex]-\frac32[/latex]
    4. [latex]4[/latex]
      1. [latex]-\frac56[/latex]
      2. [latex]\frac12[/latex]
      3. [latex]-10[/latex]
      1. [latex]57[/latex]
      2. [latex]5[/latex]
      3. [latex]\frac{19}2[/latex]
      1. [latex]-26[/latex]
      2. [latex]-2[/latex]
      3. [latex]4[/latex]
      1. [latex]-13[/latex]
      2. [latex]-\frac{89}{16}[/latex]
      3. [latex]-\frac{41}4[/latex]

    1. An intercept is a point where a graph touches the x- or y-axis.
      1. y-intercept: (0, 2); x-intercept: (-5, 0)
      2. y-intercept: (0, -2); x-intercepts: (-2, 0), (1, 0)

      1. Yes
      2. No

  1. Infinity and negative infinity; Discuss with classmates.

Classwork: Graphing Quadratic Functions

  1. 1
  2. none
  3. 1

Graph A

  1. [latex]x=3[/latex]
  2. [latex](3,4)[/latex]
  3. maximum
  4. Domain [latex]=\left(-\infty,\infty\right);[/latex] Range [latex]=(-\infty,4\rbrack[/latex]
  5. [latex](0,-5)[/latex]
  6. The points are symmetric across the axis of symmetry.

Graph B

  1. [latex]x=-2[/latex]
  2. [latex](-2,-5)[/latex]
  3. maximum
  4. D [latex]=\left(-\infty,\infty\right);[/latex] R [latex]=\lbrack-5,\infty)[/latex]
  5. [latex](0,-1)[/latex]
  6. The points are symmetric across the axis of symmetry.

    1. Up
      Axis of symmetry: [latex]x=3[/latex]
      Vertex: [latex](3,4)[/latex]
      y-intercept: [latex](0,13)[/latex]
      Number of x-intercepts: none
      Domain : [latex]\left(-\infty,\infty\right)[/latex]
      Range: [latex]\lbrack4,\infty)[/latex]
    2. Down
      Axis of symmetry: [latex]x=-1[/latex]
      Vertex: [latex](-1,0)[/latex]
      y-intercept: [latex](0,-1)[/latex]
      Number of x-intercepts: 1
      Domain : [latex]\left(-\infty,\infty\right)[/latex]
      Range: [latex](-\infty,0\rbrack[/latex]
    3. Down
      Axis of symmetry: [latex]x=2[/latex]
      Vertex: [latex](2,7)[/latex]
      y-intercept: [latex](0,3)[/latex]
      Number of x-intercepts: 2
      Domain : [latex]\left(-\infty,\infty\right)[/latex]
      Range: [latex](-\infty,7\rbrack[/latex]
    4. Down
      Axis of symmetry: [latex]x=-5[/latex]
      Vertex: [latex](-5,-7)[/latex]
      y-intercept: [latex](0,-82)[/latex]
      Number of x-intercepts: none
      Domain : [latex]\left(-\infty,\infty\right)[/latex]
      Range: [latex](-\infty,-7\rbrack[/latex]

Homework: Graphing Quadratic Functions

  1. Explain.
  2. Up
    Axis of symmetry: [latex]x=-5[/latex]
    Vertex: [latex](-5,1)[/latex]
    y-intercept: [latex](0,26)[/latex]
    Number of x-intercepts: none
    Domain : [latex]\left(-\infty,\infty\right)[/latex]
    Range: [latex]\lbrack1,\infty)[/latex]
  3. Down
    Axis of symmetry: [latex]x=2[/latex]
    Vertex: [latex](2,8)[/latex]
    y-intercept: [latex](0,0)[/latex]
    Number of x-intercepts: 2
    Domain : [latex]\left(-\infty,\infty\right)[/latex]
    Range: [latex](-\infty,8\rbrack[/latex]
    Explain.
  4. Down
    Axis of symmetry: [latex]x=-4[/latex]
    Vertex: [latex](-4,0)[/latex]
    y-intercept: [latex](0,-16)[/latex]
    Number of x-intercepts: 1
    Domain : [latex]\left(-\infty,\infty\right)[/latex]
    Range: [latex](-\infty,0\rbrack[/latex]
    Explain.
  5. Down
    Axis of symmetry: [latex]x=-1[/latex]
    Vertex: [latex](1,-2)[/latex]
    y-intercept: [latex](0,-3)[/latex]
    Number of x-intercepts: none
    Domain : [latex]\left(-\infty,\infty\right)[/latex]
    Range: [latex](-\infty,-2\rbrack[/latex]
  6. Up
    Axis of symmetry: [latex]x=-4[/latex]
    Vertex: [latex](4,-2)[/latex]
    y-intercept: [latex](0,30)[/latex]
    Number of x-intercepts: 2
    Domain : [latex]\left(-\infty,\infty\right)[/latex]
    Range: [latex]\lbrack-2,\infty)[/latex]
  7. Answers may vary.

Prep for Applications of Quadratic Functions


    1. meters per second
    2. 58.8 m
    3. [latex]D\left(t\right)=-4.9t^2+19.6t+58.8[/latex]
    4. The distance from the ground in meters
    5. When does the object strike the ground?
    1. feet per second
    2. height above the ground
    3. feet
    4. time
    5. seconds
    6. the graph is a parabola opening down.
    1. seconds
    2. meters
    3. seconds
    1. feet
    2. seconds

  1. Discuss
  2. exact
  3. approximate
  4. exact
  5. approximate
  6. exact
  7. approximate
  8. [latex]=[/latex]
  9. [latex]\approx[/latex]
  10. [latex]\approx[/latex]
  11. [latex]=[/latex]
  12. [latex]\approx[/latex]
  13. [latex]\approx[/latex]
  14. [latex]\approx[/latex]
  15. [latex]=[/latex]
  16. [latex]\approx[/latex]
  17. [latex]3,600[/latex]
  18. [latex]45[/latex]
  19. [latex]39.82[/latex]
  20. [latex]72.49[/latex]
  21. [latex]-3.094[/latex]
  22. [latex]0.3[/latex]
  23. [latex]0.3[/latex]
  24. [latex]0.59[/latex]

Classwork: Applications of Quadratic Functions

    1. 8 sec
    2. 256 ft
      1. 192 ft
      2. Up
      1. 192 ft
      2. Down
    3. 1 second, 7 seconds
    4. from 0 to 1 because it covered more distance.
    5. Domain [latex]=\left[0,8\right][/latex]; Range [latex]=\left[0,256\right][/latex]
    1. [latex](0,0)[/latex]
    2. Discuss
    3. Discuss
    4. x-intercept is used for domain; vertex is used for range
    1. x y
      0 23
      3 311
      6 311
      9 23
      10 −137
    2. 23 ft
    3. 311 ft
    4. 347 ft
    5. between 9 and 10 secs
    1. 2 meters
    2. [latex]2.30625[/latex] meters
    3. The ball is never above 3 meters
  1. The skateboarder is about 0.86 ft above the ground at the bottom of the half-pipe. The bottom of the half-pipe is 6.75 ft away from the starting point of the ride.
    1. 25 feet
    2. 25 feet at [latex]t=0[/latex]
    1. No, the maximum height is [latex]12.25[/latex] feet.
    2. 6 feet

Homework: Applications of Quadratic Functions

    1. x y
      0 80
      1 124
      2 136
      3 116
      4 64
      5 −20
    2. 80 ft
    3. 134 ft
    4. 136.25 ft
    5. between 4 and 5 seconds
    1. 8 feet
    2. 0.625 seconds
    3. 14.25 feet
    1. [latex](0, 0)[/latex]
    2. Discuss
    3. Discuss
    4. x-intercept is used for domain; vertex is used for range
    5. Answers may vary
    1. 33 feet
    2. 0.375 seconds
    3. 35.25 feet
    1. There are 4,540 parking spaces at 7 A.M.
    2. There are only 40 parking spaces at 10 A.M.
  1. The maximum height is 52 meters at time [latex]t=0[/latex]

Prep for Solving Using Quadratic Formula


      1. 5
      2. 10
      3. [latex]\sqrt{889}[/latex]
      4. Discuss with a classmate

      1. [latex]2\sqrt{3}[/latex]
      2. [latex]6\sqrt{2}[/latex]
      3. [latex]\frac{7 \pm \sqrt{3}}{2}[/latex]
      4. [latex]-1, 7[/latex]
      5. [latex]1 \pm \sqrt{5}[/latex]
      6. [latex]\frac{5\pm\sqrt5}2[/latex]

    1. [latex]6i[/latex]
    2. [latex]6i\sqrt{2}[/latex]
    3. [latex]\frac{2}{5}i[/latex]
    4. [latex]-3 \pm \frac{3}{2}i[/latex]
    5. [latex]\frac{5}{2} \pm \frac{3\sqrt{2}}{2}i[/latex]
    6. [latex]2 \pm 3i[/latex]

Classwork: Solving Using the Quadratic Formula

      1. [latex]x = 2 \pm \sqrt{7}[/latex]
      2. [latex]x = \pm i\sqrt{3}[/latex]
      3. [latex]x = \frac{-5 \pm \sqrt{33}}{2}[/latex]
      4. [latex]x = \frac{3}{2} \pm \frac{\sqrt{11}}{2}i[/latex]
      5. [latex]x = -3[/latex]
      6. [latex]x = \frac{3 \pm \sqrt{13}}{4}[/latex]
      7. [latex]x = \frac{3 \pm \sqrt{29}}{10}[/latex]
      8. [latex]x = \frac{7}{2} \pm \frac{\sqrt{23}}{2}i[/latex]
      9. [latex]x = \pm \frac{5}{2}i[/latex]
      10. [latex]x = 4, -\frac{1}{2}[/latex]
      11. [latex]x = \frac{-1 \pm \sqrt{11}}{4}[/latex]
      12. [latex]x = \frac{9}{2}, 0[/latex]

      1. 2
      2. 1
      3. none
      4. Discuss.
      5. Check with your classmate.

      1. Down
        Axis of symmetry: [latex]x=1[/latex]
        Vertex: (1,3)
        y-intercept: (0,1)
        x-intercepts: [latex]\left(\frac{2\pm\sqrt6}2,0\right)[/latex]
        Domain: [latex]\left(-\infty,\infty\right)[/latex]
        Range: [latex](-\infty,3\rbrack[/latex]

      1. 293 feet
      2. 329 feet
      3. 2 seconds, 7 seconds
      4. 9.03 seconds
      5. Domain [latex]=[0,9.03][/latex]; Range [latex]=0,329[/latex]
    1. ~2.33 sec

Homework: Solving Using the Quadratic Formula

      1. [latex]5\sqrt{7}[/latex]
      2. [latex]3 \pm \frac{\sqrt{3}}{2}[/latex]
      3. [latex]10i\sqrt{3}[/latex]
      4. [latex]5 \pm \frac{i\sqrt{30}}{2}[/latex]

      1. [latex]x = \frac{7}{2}, -\frac{5}{3}[/latex]
      2. [latex]x = \frac{17}{20}, -\frac{10}{29}[/latex]
      3. [latex]x = \frac{5 \pm \sqrt{109}}{6}[/latex]
      4. [latex]x = \pm \frac{\sqrt{2}}{4}[/latex]
      5. [latex]x = 4 \pm \sqrt{6}[/latex]
      6. [latex]x = -\frac{3}{4} \pm \frac{\sqrt{51}}{4}i[/latex]
      7. [latex]x = \frac{1}{3} \pm \frac{\sqrt{71}}{3}i[/latex]
      8. [latex]x = 1[/latex]
      9. [latex]x = \frac{5 \pm \sqrt{17}}{2}[/latex]
      10. [latex]x = 0, 2[/latex]
      11. Explain.
      12. Discuss.
      13. Check with a classmate.

      1. Down
        Axis of symmetry: [latex]x=3[/latex]
        Vertex: (3,3)
        y-intercept: (0,-15)
        x-intercepts: [latex]\left(\frac{6\pm\sqrt6}2,0\right);[/latex]
        Domain: [latex]\left(-\infty,\infty\right)[/latex]
        Range: [latex](-\infty,3\rbrack[/latex]

    1. 1.57 seconds
    2. 1.45 seconds
    3. [latex]\approx10.32[/latex] seconds longer
      1. 2 seconds
      2. 382 feet
      3. Domain [latex]=[0,4.763][/latex]; Range [latex]=[0,382][/latex]

Classwork: Solving Using the Square Root Method

    1. [latex]x = \pm 4[/latex]
    2. [latex]x = \pm 10[/latex]
    3. [latex]x = \pm 5i[/latex]
    4. [latex]x = \pm 9i[/latex]
    5. [latex]x = \pm i\sqrt{3}[/latex]
    6. [latex]x = \pm i[/latex]
    7. [latex]x = \pm \sqrt{15}[/latex]
    8. [latex]x = \pm \frac{3\sqrt{11}}{2}[/latex]
    9. [latex]x = \pm 4[/latex]
    10. [latex]x = \pm \frac{2\sqrt{2}}{7}i[/latex]
    11. [latex]x = \pm 2\sqrt{3}[/latex]
    12. [latex]x = \pm \sqrt{41}[/latex]
    13. [latex]x = \pm \sqrt{3}[/latex]
    14. [latex]x = \pm \sqrt{23}[/latex]
    15. [latex]x = \pm 8[/latex]
    16. [latex]x = \pm \frac{2}{3}i[/latex]

    1. 1.25 seconds
    2. [latex]x=\pm\frac{\sqrt5}3[/latex]
    3. Explain.
    4. Discuss.

Homework: Solving Using the Square Root Method

  1. Many answers possible.
      1. [latex]x = \pm 7[/latex]
      2. [latex]x = \pm \sqrt{3}[/latex]
      3. [latex]x = \pm 2i[/latex]
      4. [latex]x = \pm \frac{9}{2}i[/latex]
      5. [latex]x = \pm \sqrt{46}[/latex]
      6. [latex]x = \pm 2\sqrt{7}[/latex]

      1. Up
        Axis of symmetry: [latex]x=0[/latex]
        Vertex:[latex](0,-5)[/latex]
        y-intercept: [latex](0,-5)[/latex]
        x-intercepts: [latex]\left(\pm\frac{\sqrt5}2,0\right)[/latex]
        Domain:[latex]\left(-\infty,\infty\right)[/latex]
        Range: [latex]\lbrack-5,\infty)[/latex]

    1. 3.26 seconds
    2. Answers may vary
    3. Many answers possible.

Prep for Solving Equations by Factoring


      1. [latex]10(y^2 + 1)[/latex]
      2. [latex]3t(t + 2)[/latex]
      3. [latex]3x^2(5 - 7x^3)[/latex]
      4. [latex]6x^4(4 + 5x^3)[/latex]
      5. [latex]6(x^2 - 4x + 5)[/latex]
      6. [latex]2x(4x^2 + 6x - 5)[/latex]
      7. [latex](5x + 2y)(3z + 4)[/latex]
      8. [latex](6x^2 + 5)(4x - 7)[/latex]
      9. [latex]3x(x - 1)(y - 2)[/latex]
      10. [latex](3x - 2)(3y + 10x)[/latex]
      11. [latex]2(4x - 5)(7x + 3y)[/latex]
      12. [latex](4x - 5)(2y + 3)[/latex]

      1. [latex](x - 2)(x - 4)[/latex]
      2. [latex](x + 1)(x - 15)[/latex]
      3. [latex](x - 4)(x + 7)[/latex]
      4. [latex](x - 3)^2[/latex]
      5. [latex](x + 5)(x - 2)[/latex]
      6. [latex](x - 5)(x + 3)[/latex]
      7. [latex]7(x - 5)(x - 1)[/latex]
      8. [latex]3(x + 4)(x - 2)[/latex]
      9. [latex](2x - 1)(3x + 2)[/latex]
      10. [latex](5x - 4)(x - 2)[/latex]
      11. [latex](3x - 2)(x + 5)[/latex]
      12. Prime
      13. [latex](4x - 3)(2x + 3)[/latex]
      14. [latex](5x + 7)(2x + 1)[/latex]
      15. [latex](x - 2)(3x + 1)[/latex]
      16. [latex](3x - 2)(4x + 3)[/latex]

    1. [latex](x + 7)(x - 7)[/latex]
    2. [latex](2x + 9)(2x - 9)[/latex]
    3. Prime
    4. [latex]2x(4x + 1)(4x - 1)[/latex]
    5. [latex]25(x^2 + 4)[/latex]
    6. [latex](7 - x)(7 + x)[/latex]
    7. [latex]x(x + 1)(x - 1)[/latex]
    8. [latex]3x(x + 2)(x - 2)[/latex]

Classwork: Solving Equations by Factoring

      1. [latex]x = \frac{4}{3}, -\frac{4}{3}[/latex]
      2. [latex]x = -7, -1[/latex]
      3. [latex]x = -3, -\frac{1}{2}[/latex]
      4. [latex]x = 3[/latex]
      5. [latex]x = -\frac{5}{2}, 0[/latex]
      6. [latex]t = -3, -6[/latex]
      7. [latex]x = 0, \frac{1}{2}[/latex]
      8. [latex]x = -2, \frac{3}{4}[/latex]
      9. [latex]x = -\frac{1}{5}, -\frac{8}{5}[/latex]
      10. [latex]x = -2, 2[/latex]
      11. [latex]x = 8, -8[/latex]
      12. [latex]t = \frac{7}{4}, -\frac{7}{4}[/latex]
      13. [latex]x = 2, \frac{3}{4}[/latex]
      14. [latex]x = -\frac{5}{3}, -\frac{6}{5}[/latex]
      15. [latex]x = 5, -\frac{7}{2}[/latex]
      16. [latex]t = \frac{3}{2}, -\frac{8}{3}[/latex]
      17. [latex]x = -\frac{3}{2}, \frac{25}{6}[/latex]
      18. [latex]x = \frac{2}{5}, \frac{1}{3}, 0[/latex]
      19. [latex]x = \frac{7}{3}, \frac{4}{3}[/latex]
      20. [latex]x = 0, -\frac{3}{4}, \frac{3}{2}[/latex]
      21. [latex]t = -\frac{1}{3}, \frac{2}{5}[/latex]
      22. [latex]x = -\frac{3}{4}, \frac{2}{3}[/latex]
      23. [latex]x = 3, \frac{2}{7}[/latex]
      24. [latex]x = -4, -\frac{1}{6}[/latex]
      25. [latex]x=-\frac49,\frac49[/latex]
      26. [latex]x = 2, -2[/latex]

      1. Up
        Axis of symmetry:[latex]x=-2[/latex]
        Vertex:[latex](-2,-8)[/latex]
        y-intercept:[latex](0, 0)[/latex]
        x-intercepts:[latex](0, 0),(-4, 0)[/latex]
        Domain: [latex]\left(-\infty\right)[/latex]
        Range: [latex]\lbrack-8,\infty)[/latex]

      1. 8 second, 7 seconds
      2. 1
    1. [latex]x=0,-3[/latex]
    2. Explain.

Homework: Solving Equations by Factoring

      1. [latex]x = -3, -5[/latex]
      2. [latex]t = \pm \frac{5}{2}[/latex]
      3. [latex]x = \frac{5}{3}, -\frac{3}{2}[/latex]
      4. [latex]x = 0, -10[/latex]
      5. [latex]t = -\frac{3}{2}[/latex]
      6. [latex]x = 6, -\frac{1}{4}[/latex]
      7. [latex]x = \frac{4}{3}[/latex]
      8. [latex]x = -\frac{4}{3}, 3[/latex]
      9. [latex]x = 0, -6, 2[/latex]
      10. [latex]x = -\frac{2}{3}, -\frac{4}{3}[/latex]
      11. [latex]x = 0, \frac{1}{5}[/latex]
      12. [latex]t = -3, -\frac{3}{2}[/latex]
      13. [latex]t = 4, \frac{3}{5}[/latex]
      14. [latex]x = 0, \pm \frac{3}{2}[/latex]
      15. [latex]x = -6, \frac{1}{4}, 0[/latex]
      16. [latex]x = -\frac{5}{2}, 1[/latex]
      17. [latex]x = 0, \frac{1}{4}[/latex]
      18. [latex]x = 5, -5[/latex]
      19. [latex]t = \frac{4}{5}, -\frac{2}{3}[/latex]
      20. [latex]x = -\frac{5}{2}, \frac{3}{4}[/latex]
      21. Answers may vary.

      1. Down
        Axis of symmetry: [latex]x=0[/latex]
        Vertex: [latex](0,1)[/latex]
        y-intercept: [latex](0,1)[/latex]
        x-intercepts: [latex](-1,0),(1,0)[/latex]
        Domain: [latex]\left(-\infty,\infty\right)[/latex]
        Range: [latex](-\infty,1\rbrack[/latex]

      1. 1 seconds, 3 seconds
      2. 5 seconds
    1. Answers may vary.
    2. Explain.

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