SOLUTION: we're doing parabolas at the moment. I need to know how to find the turning point of a parabola, when the equation is (x-2)(x+2) for example. How do I substitute it in with the lin

Algebra ->  Test -> SOLUTION: we're doing parabolas at the moment. I need to know how to find the turning point of a parabola, when the equation is (x-2)(x+2) for example. How do I substitute it in with the lin      Log On


   

Question 771158: we're doing parabolas at the moment. I need to know how to find the turning point of a parabola, when the equation is (x-2)(x+2) for example. How do I substitute it in with the line of symmetry??
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Assuming you mean, like y=%28x-2%29%28x%2B2%29, the "turning point" would be the vertex, either a maximum point or a minimum point. Your example allows you to quickly find horizontal number line intercepts; the x value for the vertex will be in the exact middle of these horizontal x intercepts.

x-intercepts, the "zeros" of y:
%28x-2%29%28x%2B2%29=0
Either x=2 or x=-2
THOSE are the x-intercepts, where y=0, where parabola crosses the x-axis.

What is x at the vertex?
%282%2B%28-2%29%29%2F2=0
highlight%28x=0%29 is the coordinate for the vertex.

What is y coordinate at the vertex?
y=%280-2%29%280%2B2%29
y=%28-2%29%282%29
highlight%28y=-4%29

MEANING: the vertex of this parabola is (0, -4)