SOLUTION: I get Quadratic Equations, however I'm having trouble coming up with the answer in the book. It says find the rule of quadratic function whose grpah has hte given vertex and passes

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: I get Quadratic Equations, however I'm having trouble coming up with the answer in the book. It says find the rule of quadratic function whose grpah has hte given vertex and passes      Log On


   

Question 460003: I get Quadratic Equations, however I'm having trouble coming up with the answer in the book. It says find the rule of quadratic function whose grpah has hte given vertex and passes through given point.
Vertex (-1,-2) point (1,2)
Any help would be appreciated
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

The vertex form of a parabola's equation is :

y=+a%28x-h%29%5E2%2Bk+..... .... (h,k) is the vertex.
given:
Vertex (-1,-2) point (1,2)
You are given the vertex (-1-2), so the equation becomes:

y=+a%28x-%28-1%29%29%5E2%2B%28-2%29
y=a%28x%2B1%29%5E2-2

Since the parabola contains the point (1, 2), substitute these values for x and y, and then solve the equation for a:

2=a%281%2B1%29%5E2-2
2=4a-2
4=4
a=1

Now replace a with the value determined,
y=1%28x%2B1%29%5E2-2
or
y=%28x%2B1%29%5E2-2


+graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+%28x%2B1%29%5E2-2%29+