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Create a table of values for y = 2x² + 2x − 8.

Mathematics

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Answer

b(i)

x≈−2.56,x≈1.56x \approx -2.56, x \approx 1.56

Graph of y = 2x² + 2x − 8

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Key points of y = 2x² + 2x − 8
Pointxy
x-intercept−2.560
Minimum−0.5−8.5
y-intercept0−8
x-intercept1.560

Step-by-step solution

3 steps
  1. Create a table of values for y=2x2+2x−8y = 2x^2 + 2x - 8.

    To plot the graph, we need to calculate y-values for a range of x-values. We will choose x-values from −4-4 to 3 to capture the shape of the parabola, including its vertex and x-intercepts.

    y=2x2+2x−8y = 2x^2 + 2x - 8
    xxx2x^22x22x^22x2x−8-8y=2x2+2x−8y = 2x^2 + 2x - 8
    −4-41632−8-8−8-832−8−8=1632 - 8 - 8 = 16
    −3-3918−6-6−8-818−6−8=418 - 6 - 8 = 4
    −2-248−4-4−8-88−4−8=−48 - 4 - 8 = -4
    −1-112−2-2−8-82−2−8=−82 - 2 - 8 = -8
    −0.5-0.50.250.5−1-1−8-80.5−1−8=−8.50.5 - 1 - 8 = -8.5
    0000−8-80+0−8=−80 + 0 - 8 = -8
    1122−8-82+2−8=−42 + 2 - 8 = -4
    2484−8-88+4−8=48 + 4 - 8 = 4
    39186−8-818+6−8=1618 + 6 - 8 = 16
  2. Plot the graph of y=2x2+2x−8y = 2x^2 + 2x - 8.

    a)

    1. Draw and label the x-axis and y-axis on the provided graph paper.
    2. Mark the scale as specified: 1 unit for the y-axis and 1 unit for the x-axis. This means each major grid line represents 1 unit on both axes.
    3. Plot the points from the table: (−4,16)(-4, 16), (−3,4)(-3, 4), (−2,−4)(-2, -4), (−1,−8)(-1, -8), (−0.5,−8.5)(-0.5, -8.5), (0,−8)(0, -8), (1,−4)(1, -4), (2,4)(2, 4), (3,16)(3, 16).
    4. Draw a smooth curve through these points to form the parabola.
  3. Use the graph to solve the equations.

    b)

    i) Solve 2x2+2x−8=02x^2 + 2x - 8 = 0
    This equation is equivalent to finding the x-intercepts of the graph y=2x2+2x−8y = 2x^2 + 2x - 8. These are the points where the parabola crosses the x-axis (where y=0y=0).
    By observing the graph, the parabola intersects the x-axis at approximately:
    x≈−2.56x \approx -2.56 and x≈1.56x \approx 1.56.
    (For exact values: x=−2±22−4(2)(−8)2(2)=−2±4+644=−2±684=−2±2174=−1±172x = \frac{-2 \pm \sqrt{2^2 - 4(2)(-8)}}{2(2)} = \frac{-2 \pm \sqrt{4+64}}{4} = \frac{-2 \pm \sqrt{68}}{4} = \frac{-2 \pm 2\sqrt{17}}{4} = \frac{-1 \pm \sqrt{17}}{2})
    The solutions are x≈−2.56,x≈1.56\boxed{x \approx -2.56, x \approx 1.56}.

    ii) Solve 2x2+x+2=02x^2 + x + 2 = 0
    To solve

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