How do you translate #y=2sin (4x-pi/3)# from the parent function?

1 Answer
Dec 1, 2015

Start from #sin(x)#. We did the following transformations:

  1. #sin(x)\to sin(4x)#
  2. #sin(4x)\to sin(4x-pi/3)#
  3. #sin(4x-pi/3)\to 2sin(4x-pi/3)#

Let's see how these changes affect the graph:

  1. When we change #f(x)\to f(kx)#, we change the "speed" with which the #x# variable runs. This means that, if #k# is positive, the #x# values arrive earlier. For istance, if #k=4#, we have #f(4)# when #x=4#, of course. But when computing #f(4x)#, we have #f(4)# for #x=1#. This means that #sin(4x)# is a horizontally compressed version of #sin(x)#. Here's the graphs .

  2. When we change from #f(x)# to #f(x+k)#, we are translating horizontally the function, and the reasons are similar to those in the first point. Is #k# is positive, the function is shifted to the left, if #k# is negative to the right. So, in this case, the function is shifted to the right by #pi/3# units. Here's the graphs

  3. When we change from #f(x)# to #k*f(x)#, we simply multiply every point in the graph by #k#, resulting in a vertical stretch (expanding if #k>0# or contracting if #k<0#). Here's the graphs.