SOLUTION: state the transforamtion necessary to transform f(x)=1/2(2^3x)-4 to g(x)=8^x

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Question 887887: state the transforamtion necessary to transform
f(x)=1/2(2^3x)-4 to g(x)=8^x

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
%22f%28x%29%22%22%22=%22%22expr%281%2F2%29%282%5E%283x%29%29-4 to %22g%28x%29%22%22%22=%22%228%5Ex

The graph of %22f%28x%29%22 is the red graph below

graph%28640%2F3%2C400%2C-5%2C3%2C-5%2C10%2C+%281%2F2%29%282%5E%283x%29%29-4%29

Write that as:

%22f%28x%29%22%22%22=%22%22expr%281%2F2%29%28%282%5E3%29%5Ex%29-4

Then as

%22f%28x%29%22%22%22=%22%22expr%281%2F2%29%288%5Ex%29-4

Then we form h(x) by adding 4 to the right side
which shifts the graph 4 units up

%22h%28x%29%22%22%22=%22%22expr%281%2F2%29%288%5Ex%29-4%2Bred%284%29
%22h%28x%29%22%22%22=%22%22expr%281%2F2%29%288%5Ex%29

The graph of h(x) is the green graph below



Finally we form g(x) by multiplying the right side of h(x) by 2.

%22g%28x%29%22%22%22=%22%22red%282%29%2Aexpr%281%2F2%29%288%5Ex%29
%22g%28x%29%22%22%22=%22%228%5Ex
  
which stretches the green graph by a factor of 2.  That's the same as 
if the graph of h(x) were on a rubber sheet and then we stretched the 
rubber sheet to double its size.

So the final graph of %22g%28x%29%22%22%22=%22%228%5Ex is the blue graph
below:



So the transformation is first to h(x), by adding 4 to the right side:

h(x) = f(x)+4

then the second transformation is from h(x) to g(x), by multiplying the
right side of h(x) by 2, or

g(x) = 2h(x)

then you can substitute f(x)+4 for h(x) and get

g(x) = 2[f(x)+4]

or 

g(x) = 2f(x)+8

Edwin