McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
3. The Quadratic Formula and the Discriminant
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Exercise 59 Page 197

Identify the coordinates of the vertex.

y=1/4x^2

Practice makes perfect
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, ). This means that we have h= 0 and k= . We can use these values to partially write our function. y= a(x- 0)^2+ ⇔ y= ax^2 We can see in the graph that the parabola opens upwards. Therefore, a will be a positive number. To find its value, we will use a lattice point contained in the given parabola.

We can see above that the point has coordinates (4,4). Since this point is on the curve, it satisfies its equation. Hence, to find the value of a, we can substitute 4 for x and 4 for y and simplify.
y=ax^2
4=a( 4^2)
â–Ľ
Solve for a
4=a(16)
4/16=a
1/4=a
a=1/4
We found that a= 14. Now we can complete the equation of the curve. y= 1/4x^2