Question 171206: Can you PLEASE show me how to graph a quadratic function using its properties?
f(x)=x^2-4x-5
Answer by jojo14344(1513)   (Show Source):
You can put this solution on YOUR website!  ---> 
Okay, first we go for the Vertex-form of quadratic: 
where, h & k are  points on the vertex.
We'll do this by completing the square: We take  of "b" in the quadratic eq'n. and squared it. In this case it, "b"=4, so half of it -->  , then squared,  .
So we need to add "4" to the eqn:
.
 ----> remember to subtract 4 too so the expression does not change.
 ----> follows our vertex form now, where  &  . We'll see in the graph:
 ----> see points (2,-9). This will be the vertex.
Now we'll see the x-intercepts by solving the eqn:
By Quadratic Formula, where ---->
X-intercepts---->
See the graph again:
.
Thank you,
Jojo
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