Given:
The quadratic equation is
To find:
The vertex of the given quadratic equation.
Solution:
If a quadratic function is , then
We have,
It can be written as
...(i)
Here, .
Putting in (i), we get
On further simplification, we get
So, the vertex of the given quadratic equation is .
Therefore, the correct option is A.
Answer:
Please find attached the required graph of the equation, y = x² - 2·x - 8, created using MS Excel
Step-by-step explanation:
The given function required to be plot is y = x² - 2·x - 8
Therefore, the coordinates of the vertex of the parabola formed by the equation (h, k) is given as follows;
h = -(-2)/(2×1) = 1
k = 1² - 2×1 - 8 = -9
The coordinates of the vertex = (1, -9)
The roots of the equation is given when y = 0, as follows;
At the roots, we have;
x² - 2·x - 8 = 0
By factorizing, we get
x² - 2·x - 8 = (x - 4)·(x + 2) = 0
Therefore. the roots of the equation are;
x = 4, and x = -2
The coordinates of the roots are;
(4, 0), and (-2, 0)
Two other points can be found at when x = 3 and when x = 0 as follows;
When x = 3, we have;
y = 3² - 2×3 - 8 = -5
(3, -5)
When x = 0, we have;
y = 0² - 2×0 - 8 = -8
(0, -8)
The five points are;
(1, -9), (4, 0), (-2, 0), (3, -5), (0, -8)
The graph of the equation created using MS Excel showing the five points is attached.
