Big Ideas Math Algebra 1, 2015
BI
Big Ideas Math Algebra 1, 2015 View details
4. Graphing f(x) = a(x - h)² + k
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Exercise 4 Page 441

Practice makes perfect
a Let's review the effects of the parameters a and h on a function of the form y = a(x-h)^2.

A quadratic function of the form y = a(x-h)^2 is a transformation of the quadratic parent function f(x) =x^2.

  • If a<0 the graph is reflected in the x-axis.
  • If 0 < |a| <1 the graph is vertically shrunk.
  • If 1 < |a| the graph is verticalyl stretched.
  • If h>0 the graphs is horizontally translated h units to the right.
  • If h<0 the graphs is horizontally translated |h| units to the left.

    We can now identify the value of the parameters by comparing our given function y=(x-3)^2 with the general form y = a(x-h)^2. y= a(x- h)^2 y= (1)(x- 3)^2 For this case a=1 and h= 3. Therefore, the graph will be the same as the parent function f(x)=x^2, but translated 3 units to the right.

    We can use a graphing calculator to verify our prediction.

    As we can see in the graph above, the function y=(x-3)^2 is the same as that of f(x) =x^2 but shifted 3 units to the right, as predicted.

b We will proceed just as we did in Part A. First let's identify the parameters a and h for the given function y = (x+3)^2 by comparing it to the general form y = a(x-h)^2.
y= a(x- h)^2 y= (1)(x-( - 3))^2 Hence, for this case a=1 and h= - 3. Therefore, the graph will be just as that of the parent function f(x)=x^2 but translated 3 units to the left.

We can use a graphing calculator to verify our prediction.

As we can see in the graph above, the function y=(x+3)^2 is the same as that of f(x) =x^2 but shifted 3 units to the left, as predicted.

c We will proceed just as we did in previous in the parts. First let's identify the parameters a and h for the given function y = -(x-3)^2 by comparing it to the general form y = a(x-h)^2.
y= a(x- h)^2 y= (- 1)(x- 3)^2 Then, for this case a=- 1 and h= 3. Therefore, the graph will be similar to that of the parent function f(x)=x^2 but translated 3 units to the right, and reflected in the x-axis.

We can use a graphing calculator to verify our prediction.

As we can see in the graph above, the function y=-(x-3)^2 is the same as that of f(x) =x^2, but shifted 3 units to the right and reflected in the x-axis. This confirms our prediction.