Big Ideas Math Algebra 1, 2015
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Big Ideas Math Algebra 1, 2015 View details
4. Graphing f(x) = a(x - h)² + k
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Exercise 74 Page 448

To find the function for h(x), multiply 13 by the function f(x).

Describe the Transformation: The graph of h(x) is a vertical compression by a factor of 13 of the graph of f(x).
Equation for h(x): h(x)=- 1/3(x+5)^2-2

Practice makes perfect
To describe the transformation, we need to identify the values of a, h, and k for h(x). h(x)=1/3f(x) ⇕ h(x)= 1/3f(x- 0)+ 0 We can see above that a= 13, h= 0, and k= 0. Let's recall how to transform the graph of a quadratic function given these values.
f(x)=a(x-h)^2+k
h - Horizontal Translation

& h units right if h is positive & |h| units left if h is negative

k - Vertical Translation

& k units up if k is positive & |k| units down if k is negative

a - Orientation and Shape
If a<0, the graph is reflected across the x-axis

& If |a|>1, the graph is stretched vertically & If 0<|a|<1, the graph is compressed vertically

Since h= 0 and k= 0, the graph of f(x) will not be translated horizontally or vertically. The value a= 13 represents a vertical compression by a factor of 13.

Equation for h(x)

In order to the find the function for h(x), mutiply 13 by f(x)=-(x+5)^2-6.
f(x)=-(x+5)^2-6.
1/3f(x)= 1/3(-(x+5)^2-6)
1/3f(x)=((1/3 * -1 )(x+5)^2)-(1/3 * 6)
1/3f(x)=- 1/3(x+5)^2-2
The function for h(x) in terms of x is h(x)=- 13(x+5)^2-2.