The problem requires us to complete a table of values for the equation $y = 2x^2 - 7x - 9$ for $-3 \le x \le 6$. Then, we need to draw the graph of the equation and use the graph to estimate the roots of $2x^2 - 7x = 26$, the coordinates of the minimum point of $y$, and the range of values for which $2x^2 - 7x < 9$.

AlgebraQuadratic EquationsGraphsParabolaInequalitiesFunctions
2025/4/22

1. Problem Description

The problem requires us to complete a table of values for the equation y=2x27x9y = 2x^2 - 7x - 9 for 3x6-3 \le x \le 6. Then, we need to draw the graph of the equation and use the graph to estimate the roots of 2x27x=262x^2 - 7x = 26, the coordinates of the minimum point of yy, and the range of values for which 2x27x<92x^2 - 7x < 9.

2. Solution Steps

(a) Completing the table of values:
We need to calculate the yy values for x=1,2,4,6x = -1, 2, 4, 6.
For x=1x = -1:
y=2(1)27(1)9=2+79=0y = 2(-1)^2 - 7(-1) - 9 = 2 + 7 - 9 = 0
For x=2x = 2:
y=2(2)27(2)9=8149=15y = 2(2)^2 - 7(2) - 9 = 8 - 14 - 9 = -15
For x=4x = 4:
y=2(4)27(4)9=32289=5y = 2(4)^2 - 7(4) - 9 = 32 - 28 - 9 = -5
For x=6x = 6:
y=2(6)27(6)9=72429=21y = 2(6)^2 - 7(6) - 9 = 72 - 42 - 9 = 21
The completed table is:
x | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6
---|----|----|----|---|---|----|----|----|----|----
y | 13 | | 0 | -9| -14| -15| -12| -5| 6 | 21
(b) Drawing the graph:
Using a scale of 2 cm to 1 unit on the x-axis and 2 cm to 4 units on the y-axis, we can plot the points from the completed table and draw a smooth curve through them to represent the graph of y=2x27x9y = 2x^2 - 7x - 9. Since the graph is not provided here, it's impossible to give an exact answer to part (c). I can only provide a general method.
(c) Estimating from the graph:
(i) Roots of 2x27x=262x^2 - 7x = 26:
This is equivalent to solving 2x27x26=02x^2 - 7x - 26 = 0.
To solve this graphically, we can rewrite the equation as 2x27x9=172x^2 - 7x - 9 = 17. This means we want to find the xx values where the graph y=2x27x9y = 2x^2 - 7x - 9 intersects the line y=17y = 17.
Find the points of intersection of the curve and the horizontal line y=17y=17, and the xx-coordinates of these points are the roots.
(ii) Coordinates of the minimum point of yy:
The minimum point is the vertex of the parabola. Find the coordinates of the lowest point on the graph.
(iii) Range of values for which 2x27x<92x^2 - 7x < 9:
This is equivalent to 2x27x9<02x^2 - 7x - 9 < 0, which means we are looking for the xx values where the graph of y=2x27x9y = 2x^2 - 7x - 9 is below the x-axis (y=0y=0). The range of xx values between the two roots of the equation 2x27x9=02x^2-7x-9 = 0 satisfy this inequality.
The roots of 2x27x9=02x^2-7x-9=0 can be read from the graph where y=0y=0. From the completed table in (a) we have x = -1 and x = 4.5 are approximately the roots.
Therefore, 1<x<4.5-1 < x < 4.5.

3. Final Answer

(a) Completed table:
x | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6
---|----|----|----|---|---|----|----|----|----|----
y | 13 | 13 | 0 | -9| -14| -15| -12| -5| 6 | 21
(b) Graph: Not provided.
(c) Estimates from the graph (approximate):
(i) Roots of 2x27x=262x^2 - 7x = 26: The x values where y=
1

7. These would need to be read off the actual graph to give a numerical answer.

(ii) Coordinates of the minimum point of yy: Approximate value would need to be read off the actual graph to give a numerical answer.
(iii) Range of values for which 2x27x<92x^2 - 7x < 9: 1<x<4.5-1 < x < 4.5

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