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Thursday, 13 September 2012

Sept. 13 Class

Learning Goals:

  • Sketch a quadratic function with multiple transformations.
  • Write an equation from a graph of a quadratic function.
Today we did a formative quiz on function notation.  I will get these back to you as soon as I mark them.

Next I discussed the order in which we should perform transformations.  When you have multiple transformations, you should state any Stretches first, then Reflections then Translations.  Remember SRT.

I then worked out some examples.

Next I discussed how to write the equation of a quadratic function from looking at the graph.

Example Write the equation for the following quadratic function.


Solution  First we look at the the vertex (3, 0).  That means we have h = 3 and k =0.  Next we count one unit over from the vertex and we see that the graph drops down by 2.  That means a = -2.  Thus the equation of the graph is:

f(x) = -2(x–3)²

HINT: for homework questions you can check if you got it right by using a graphing calculator.  Here is a link to online graphing calculator.


Try entering the above equation and see if you get the same graph (make sure you use the * button between the 2 and the bracket to multiply.)

Homework
P. 56 #1 - 11

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