1. Quadratic equations only occurs when two linear equations are multiplied with each other, provided that x² is the greatest power in the equation.
e.g y = (x+2)(x-4)
= x² - 2x - 8
3. The roots of the resultant quadratic equation are the same as the individual linear equations
4. Calculate turning point:
x = turning point = (root) + (root) / 2
e.g x = 1 = 4 + (-2) / 2
Refer to pic above
Putting on your thinking cap:
Why, for point number 4, must the (root)+(root) be divided by 2?