Stretch And Shrinking Graph? Please explain this to me, and chug some number examples

http://library.thinkquest.org/20991/...etchshrink.gif
When y = a * f(x), multiply the y values of f(x) by a. Leave the x values alone. This is a vertical stretch (if |a| > 1) or shrink (if |a| < 1). Example: 1. Problem: Given is a graph of y = f(x). Sketch y = 2f(x). The figure below is the graph of f(x).http://library.thinkquest.org/20991/media/alg2_vsp.gif
Solution: Multiply values of y by 2 and keep the same x values. Then redraw the graph. The figure below is the graph of the solution.http://library.thinkquest.org/20991/media/alg2_vss.gif

When y = f(b * x), divide the x values of f(x) by b. Leave the y values alone. This is a horizontal stretch (if |b| < 1) or shrink (if |b| > 1). Example: 2. Problem: Given is a graph of y = f(x). Sketch y = f(.5x). The figure below is the graph of y = f(x).http://library.thinkquest.org/20991/media/alg2_hsp.gif
Solution: Divide each x value by .5 (same as multiplying by 2). Keep same y values, and redraw the graph. The figure below is a graph of the solution.








http://library.thinkquest.org/20991/media/alg2_hss.gif

what do you want done to the problem/ what do you need help with?

Quote:

---

Originally Posted by Gordon

http://library.thinkquest.org/20991/...etchshrink.gif
When y = a * f(x), multiply the y values of f(x) by a. Leave the x values alone. This is a vertical stretch (if |a| > 1) or shrink (if |a| < 1). Example: 1. Problem: Given is a graph of y = f(x). Sketch y = 2f(x). The figure below is the graph of f(x).http://library.thinkquest.org/20991/media/alg2_vsp.gif
Solution: Multiply values of y by 2 and keep the same x values. Then redraw the graph. The figure below is the graph of the solution.http://library.thinkquest.org/20991/media/alg2_vss.gif

When y = f(b * x), divide the x values of f(x) by b. Leave the y values alone. This is a horizontal stretch (if |b| < 1) or shrink (if |b| > 1). Example: 2. Problem: Given is a graph of y = f(x). Sketch y = f(.5x). The figure below is the graph of y = f(x).http://library.thinkquest.org/20991/media/alg2_hsp.gif
Solution: Divide each x value by .5 (same as multiplying by 2). Keep same y values, and redraw the graph. The figure below is a graph of the solution.








http://library.thinkquest.org/20991/media/alg2_hss.gif

---

Are you asking us to check your work? If so, it's fine...

Sorry, i forgot =), my question was how are does thing really work? like how do you kow how to move these things whenever you use the formula y=a*x stuff those are the part i don't get. And how are the releated to real life situation?