Quadratic Function Equations
To find the equation of a parabola given the vertex and the zeroes, we can use the intercept form equation to help us:
[tex]y=a(x-r)(x-s)[/tex]
- r and s = intercepts/zeros of the graph
Solving the Question
We're given:
- Zeros: -8, 4
- Maximum: (-2, 18)
[tex]y=a(x-r)(x-s)[/tex]
⇒ Plug in the given information:
[tex]y=a(x-(-8))(x-4)\\18=a(-2-(-8))(-2-4)\\18=a(-2+8)(-2-4)\\18=a(6)(-6)\\18=a(-36)\\1=-2a\\\\a=-\dfrac{1}{2}[/tex]
Answer
[tex]a=-\dfrac{1}{2}[/tex]
