McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
2. Parabolas
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Exercise 1 Page 603

The standard form of a quadratic function is y=a(x-h)^2+k.

Standard Form: y = 2(x-6)^2-32
Vertex: (6, - 32)
Axis of Symmetry: x=6
Direction of Opening: upwards

Practice makes perfect

We want to write the equation in the standard form, identify the vertex, axis of symmetry, and direction of opening of the parabola.

Standard Form

We will first express the given equation in standard form, y=a(x-h)^2+k, where a, h, and k are either positive or negative constants.
y=2x^2-24x+40
y = 2(x^2-12x)+40
y = 2(x^2-12x+36)+40-2(36)
y = 2(x-6)^2+40-2(36)
y = 2(x-6)^2+40-72
y = 2(x-6)^2-32

It is important to note that we do not need to graph the parabola to identify the desired information. Let's compare the general formula for the standard form to our equation. Standard form:y=& a(x- h)^2+ k Equation:y=& 2(x- 6)^2+( - 32) We can see that a= 2, h= 6, and k= - 32.

Vertex

The vertex of a quadratic function written in standard form is the point ( h, k). For this exercise, we have h= 6 and k= - 32. Therefore, the vertex of the given equation is ( 6, - 32).

Axis of Symmetry

The axis of symmetry of a quadratic function written in standard form is the vertical line with equation x= h. As we have already noticed, for our function, this is h= 6. Therefore, the axis of symmetry is the line x= 6.

Direction of opening

Let's recall that if a>0, the parabola opens upwards. Conversely, if a<0, the parabola opens downwards. In the given function, we have a= 2, which is greater than 0. This means that the parabola opens upwards.