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F(x)=|x|-7 describe the transformation of each function compared to its parent function

User Dmn
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2 Answers

7 votes
7 votes
With this question, it is incredibly essential that you consider each transformation separately to prevent confusion.
First, the negative on the top of the fraction indicates that there is a reflection. This means that you will be filling in quadrants II and IV rather than I and III prior to the other transformations.
Dilation is indicated by the 3 in the numerator of the fraction and will actually affect the main points marked on the graph. For the parent function y= 1/x, the coordinate (1,1) is the main point in the first quadrant and the coordinate (-1,-1) is the main point in the third quadrant. When a dilation occurs, it dilates the x value for one of the coordinates and the y-value in the other. Since a reflection has also occurred, our initial points are (-1,1) and (1,-1) so the points in the second quadrant will be (-1,3) and (-3,1) as compared to the asymptotes (multiple translations have also occurred) and the points in the fourth quadrant will be (1,-3) and (3,-1) as compared to the asymptotes.
Lastly, let's consider translations: a horizontal translation involves the addition or subtraction of a number from x in the denominator of the fraction whereas a vertical translation involves the addition or subtraction of a number from (1/x), completely separate from the fraction. Therefore, the -2 is part of a horizontal translation and the +4 is part of a vertical translation. I always tell my students that the direction of the vertical translation(up or down) will be what you would assume, but the direction of the horizontal translation (right or left) will be the exact opposite of your assumption. For this reason, the -2 would indicate a shift to the right 2 units and the +4 would indicate a shift upwards 4 units. This would result in a shift of the vertical asymptote to the right 2 units and a shift in the horizontal asymptote upwards 4 units. The horizontal asymptote is written as y = 4 and the vertical is written as x=2
User Holger Frohloff
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19 votes
19 votes

Compared to the parent function f(x)=|x|, the graph of F(x) is a translation 7 units down.

User Micah Stubbs
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