Problem

6. Let $f(x)=x+4$ and $g(x)=(x-2)^{2}$. Find a function $u$ so that $f(g(u(x)))=4 x^{2}-8 x+8$.

Answer

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Answer

$$\boxed{u(x) = 2x-4}$$

Steps

Step 1 :First, we find the composition of functions $f(g(x))$.

Step 2 :$$f(g(x)) = f((x-2)^2) = (x-2)^2 + 4$$

Step 3 :Now, we want to find a function $u(x)$ such that $f(g(u(x))) = 4x^2 - 8x + 8$.

Step 4 :We can rewrite the given function as:

Step 5 :$$4x^2 - 8x + 8 = (2x-4)^2$$

Step 6 :Comparing this with the expression for $f(g(x))$, we can see that $u(x) = 2x-4$.

Step 7 :So, the function $u(x)$ is:

Step 8 :$$\boxed{u(x) = 2x-4}$$

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