Practice Test
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We want to write the equation of the given parabola. To do so, let's recall the vertex form of a quadratic function. y= a(x- h)^2+ k In this expression, a, h, and k are either positive or negative constants. Let's start by identifying the vertex.
The vertex of this parabola has coordinates ( 0, 2). This means that we have h= 0 and k= 2. We can use these values to partially write our function. y= a(x-( 0))^2+ 2 ⇕ y= ax^2+2 We can see in the graph that the parabola opens downwards. Thus, a will be a negative number. To find its value, we will use a point that lies on the parabola. Let's choose the point (1,- 1).
x= 1, y= - 1
Calculate power
a * 1=a
LHS-2=RHS-2
Rearrange equation