The equation a(x−h)2+k
means that the vertex of the parabola is at the point (h,k)
. If a
is positive, the graph opens up, and if a
is negative, the graph opens down.
h
is the negative of the x-coordinate in of the vertex, and k
is the y-coordinate. If your vertex is (−1,1)
, thenh=?
k=?
Since the x-coordinate of your vertex is -1, h=−(−1)=1
, and since the y-coordinate is 1, k=1
. Now we still have to find what a
is.
First, since the parabola is opening downwards, a
is negative. But what's the value?
Well, know the point (0,0)
is on the graph, so we just plug that in to get 0=a(0+1)2+1=a+1
Solving for a
, we get a=−1
.
Your form is y=a(x−h)2+k
where a=−1
, h=−1
, and k=1
.
in the parentheses you have (x−(−1)
. The negatives cancel each other out, and you would get (x+1)
