When we perform an operation on the entire right side, it causes a VERTICAL transformation on each y-coordinate. When we perform an operation on x, it causes a HORIZONTAL transformation on each x-coordinate. When the entire right side is multiplied by -1, each y-coordinate is reflected VERTICALLY across the x-axis. When only x is multiplied by -1, each x-coordinate is reflected HORIZONTALLY across the y-axis. When the operation is on the entire right side, the shift, stretch, or shrink is as you would expect. That is: Adding to the entire right side shifts VERTICALLY UPWARD. Subtracting from the entire right side shifts VERTICALLY DOWNWARD. Multiplying the entire right side by a positive number greater than 1 causes a VERTICAL STRETCH. Multiplying the entire right side by a positive number less than 1 causes a VERTICAL SHRINK. However, when the operation is on x only, the shift, stretch, or shrink is OPPOSITE from what you would expect. Adding to x shifts LEFT. Subtracting from x shifts RIGHT. Multiplying x by a positive number greater than 1 causes a HORIZONTAL SHRINK. Multiplying x by a positive number less than 1 causes a HORIZONTAL STRETCH. -------------------------------------------------------------------------------- (a) y=2+f(-x) The transforming steps are: f(x), f(-x), 2+f(-x) We start with y=f(x) Then first we replace x by -x y=f(-x) Replacing x by -x reflects the x-coordinate of each point HORIZONTALLY across the y-axis. So (1,2) is reflected to (-1,2) Then we add 2 to the entire right side. y=2+f(-x) Adding 2 to the entire right side shifts the y-coordinate of each point 2 units VERTICALLY UPWARD. So (-1,2) is shifted VERTICALLY UPWARD to (-1,4) Answer: (-1,4) -------------------------------------------------------------------------------- (b) y= 3f(x-5)-1 The transforming steps are f(x), 3f(x), 3f(x-5), 3f(x-5)-1 We start with y=f(x) Then we multiply the entire right side by 3 y=3f(x) Multiplying the entire right side by 3 stretches VERTICALLY the y-coordinate of each point to 3 times its distance from the x-axis. So (1,2) is shifted UPWARD to (1,6) Then we subtract 5 from x y=3f(x-5) Subtracting 5 from x shifts each point 5 units HORIZONTALLY RIGHT. So (1,6) is shifted HORIZONTALLY RIGHT to (6,6) Then we subtract 1 from the entire right side. y=3f(x-5)-1 Subtracting 1 from the right side shifts the y-coordinate of each point DOWNWARD 1 unit. So (6,6) is shifted DOWNWARD to (6,5) Answer (6,5) -------------------------------------------------------------------------------- (c) y=f(3x-5)-1 The transforming steps are f(x), f(3x), f(3x-5), which must be written as, then , or f(3x-5)-1 We begin with y=f(x) Then we replace x by 3x y=f(3x) Multiplying x by 3 shrinks the x-coordinate of each point HORIZONTALLY to 1/3 of its distance from the y-axis. So the point (1,2) gets its x-coordinate shrunk to (1/3,2) Now we must calculate how much shifting we must do to x to get f(3x-5) So we factor out 3 and rewrite y=f(3x-5) as So now we can see that x has been replaced by x-5/3. Subtracting 5/3 from x shifts the x-coordinate of each point 5/3 units HORIZONTALLY RIGHT. So (1/3,2) is shifted HORIZONTALLY RIGHT to (1/3+5/3,6) or (6/3,6) or (2,6) Finally we must subtract 1 from the entire right side which shifts each y-coordinate VERTICALLY DOWNWARD. So (2,6) is shifted VERTICALLY DOWNWARD to (2,5) Answer: (2,5) Edwin