Question

PLEASE HELP AND ANSWER CORRECTLY

Answer 1

Answer:

standard form:   y = x² - 2x - 8

vertex form:  y = (x − 1)² - 9

factorized form:  y = (x + 2)(x - 4)

Step-by-step explanation:

From inspection of the graph:

• Axis of symmetry:  x = 1
• Vertex = (1, -9)
• x-intercepts = (-2, 0) and (4, 0)
• y-intercept = (0, -8)

Standard quadratic form:   y = ax² + b x + c

Vertex form of a quadratic equation:   y = a(x − h)² + k

If a > 0 then the parabola opens upwards

If a < 0 then the parabola opens downwards

(h, k) is the vertex

c is the y-intercept

Inputting the vertex into the vertex form gives:

y = a(x − 1)² - 9

  = a(x² - 2x + 1) - 9

  = ax² - 2ax - 8

Using the x-intercepts to create a quadratic equation:

y = a(x + 2)(x - 4)

  = a(x² - 2x - 8)

  = ax² - 2ax - 8a

Comparing the y-intercepts:

-8 = -8a  ⇒  a = 1

Therefore,   y = x² - 2x - 8