Answer:
Vertex form: y = -2(x - 1)²
Standard form: y = -2x² + 4x - 2
Explanation:
Given the x-intercept as the vertex, (1, 0), and the y-intercept, (0, -2) as the two points on the graph of a parabola:
We can determine the equation by substituting these given values into the vertex form of the quadratic equation:
y = a(x - h)² + k
where:
a = determines the direction of where the graph opens, and the wideness or narrowness of the parabola.
(h, k) = vertex
Solve for the value of a:
Use vertex: (1, 0) and y-intercept, (0, -2):
y = a(x - h)² + k
-2 = a(0 - 1)² + 0
-2 = a(-1)²
-2 = a(1)
-2 = a
Quadratic Equation:
Vertex form:
The quadratic equation in vertex form that matches the graph is:
y = -2(x - 1)² + 0 or y = -2(x - 1)² ⇒ This is the quadratic equation in vertex form.
Standard form:
To transform the vertex form into the standard form, y = ax² + bx + c:
Simply expand the perfect square, (x - 1)², through FOIL method before distributing -2:
y = -2(x - 1)²
y = -2(x - 1)(x - 1)
y = -2(x² -2x + 1)
y = -2x² + 4x - 2 ⇒ This is the quadratic equation in standard form.