SOLUTION: Give 6 pairs of functions f and g such that ( f o g )(x)=x^2-2x+1

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Question 891793: Give 6 pairs of functions f and g such that ( f o g )(x)=x^2-2x+1
Answer by Edwin McCravy(20059) About Me  (Show Source):
You can put this solution on YOUR website!

(fog)(x)=x²-2x+1 factors as (x-1)², which is also (-x+1)²

The easiest pair of functions is this one

f(x) = x², g(x) = x-1 

So choose f(x) = (ax+b)² and g(x) = cx+d

Then fog(x) = [a(cx+d)+b]²

Then fog(x) = [acx+ad+b]²    

You want that to come out to be either (x-1)² or (-x+1)²

1. Make up any number for a
2. Then c will have to be either the reciprocal of a or the
negative of the reciprocal of a so we'll get x if we're 
making (x-1)², or -x if we're making (-x+1)²
3, Then we choose b to make ad+b come out to be -1 if we're
making (x-1)² or +1 if we're making (-x+1)².
 
Here are 6 made up that way.  We can make up as many as we like.

%22f%28x%29%22%22%22=%22%22%284x%2B9%29%5E2,%22g%28x%29%22%22%22=%22%22expr%28-1%2F4%29x-2
fog%28x%29%22%22=%22%22%284%28expr%28-1%2F4%29x-2%29%2B9%29%5E2 
fog%28x%29%22%22=%22%22%28-x-8%2B9%29%5E2
fog%28x%29%22%22=%22%22%28-x%2B1%29%5E2
fog%28x%29%22%22=%22%22x%5E2-2x%2B1

----------------------------

%22f%28x%29%22%22%22=%22%22%285x-6%29%5E2,%22g%28x%29%22%22%22=%22%22expr%281%2F5%29x%2B1
fog%28x%29%22%22=%22%22%285%28expr%281%2F5%29x%2B1%29-6%29%5E2 
fog%28x%29%22%22=%22%22%28x%2B5-6%29%5E2
fog%28x%29%22%22=%22%22%28x-1%29%5E2
fog%28x%29%22%22=%22%22x%5E2-2x%2B1

----------------------------

%22f%28x%29%22%22%22=%22%22%282x-5%29%5E2,%22g%28x%29%22%22%22=%22%22expr%28-1%2F2%29x%2B3
fog%28x%29%22%22=%22%22%282%2A%28expr%28-1%2F2%29x%2B3%29-5%29%5E2 
fog%28x%29%22%22=%22%22%28-x%2B6-5%29%5E2
fog%28x%29%22%22=%22%22%28-x%2B1%29%5E2
fog%28x%29%22%22=%22%22x%5E2-2x%2B1

----------------------------

%22f%28x%29%22%22%22=%22%22%282x-1%29%5E2,%22g%28x%29%22%22%22=%22%22expr%281%2F2%29x
fog%28x%29%22%22=%22%22%282%2Aexpr%281%2F2%29x-1%29%5E2 
fog%28x%29%22%22=%22%22%28x-1%29%5E2
fog%28x%29%22%22=%22%22x%5E2-2x%2B1

----------------------------

%22f%28x%29%22%22%22=%22%22%28x%2B1%29%5E2,%22g%28x%29%22%22%22=%22%22-x
 fog%28x%29%22%22=%22%22%28%28-x%29%2B1%29%5E2
fog%28x%29%22%22=%22%22%28-x%2B1%29%5E2
fog%28x%29%22%22=%22%22x%5E2-2x%2B1

----------------------------

%22f%28x%29%22%22%22=%22%22%283x%2B2%29%5E2,%22g%28x%29%22%22%22=%22%22expr%281%2F3%29x-1
fog%28x%29%22%22=%22%22%283%28expr%281%2F3%29x-6%29%2B9%29%5E2 
fog%28x%29%22%22=%22%22%28x-6%2B5%29%5E2
fog%28x%29%22%22=%22%22%28x-1%29%5E2
fog%28x%29%22%22=%22%22x%5E2-2x%2B1

Edwin