Equations for Parabolas
Mathematics In a Nutshell
Given x1 and x2 (x-intercepts)
Quadratic equation is y=a(x-x1)(x-x2)
For example, if there is y=(x-1)(x-2)
In addition
if a > 0, shape is
if a < 0, shape is
Example
a)
x-intercepts are -2 and 4.
So the equation is y=(x+2)(x-4)
b)
X-intercept is 3
So, this equation is y=(x-3)^2
c)
X-intercepts are -3 and 0
Also, a(gradient) is a < 0
Thus, this graph equation is y = -x(x+3)