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 $2x^2 - 7x < 9$.
2025/4/22
1. Problem Description
The problem requires us to complete a table of values for the equation for . Then, we need to draw the graph of the equation and use the graph to estimate the roots of , the coordinates of the minimum point of , and the range of values for which .
2. Solution Steps
(a) Completing the table of values:
We need to calculate the values for .
For :
For :
For :
For :
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 . 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 :
This is equivalent to solving .
To solve this graphically, we can rewrite the equation as . This means we want to find the values where the graph intersects the line .
Find the points of intersection of the curve and the horizontal line , and the -coordinates of these points are the roots.
(ii) Coordinates of the minimum point of :
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 :
This is equivalent to , which means we are looking for the values where the graph of is below the x-axis (). The range of values between the two roots of the equation satisfy this inequality.
The roots of can be read from the graph where . From the completed table in (a) we have x = -1 and x = 4.5 are approximately the roots.
Therefore, .
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 : 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 : Approximate value would need to be read off the actual graph to give a numerical answer.
(iii) Range of values for which :