SOLUTION: Given h(x), find a pair of functions f and g such that h(x) = f<font face = "bookshelf symbol 7">g</font>g(x): h(x) = {{{sqrt( (7x^7+1)/(7x^7-1) ) }}}.

Algebra ->  Functions -> SOLUTION: Given h(x), find a pair of functions f and g such that h(x) = f<font face = "bookshelf symbol 7">g</font>g(x): h(x) = {{{sqrt( (7x^7+1)/(7x^7-1) ) }}}.       Log On


   



Question 109091: Given h(x), find a pair of functions f and g such that h(x) = fgg(x):
h(x) = sqrt%28+%287x%5E7%2B1%29%2F%287x%5E7-1%29+%29++.

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!

Given h(x), find a pair of functions f and g such that h(x) = fgg(x):
h(x) = square root sqrt%28+%287x%5E7%2B1%29%2F%287x%5E7-1%29+%29++. 

Pick g(x) as any expression in x from the whole expression

sqrt%28+%287x%5E7%2B1%29%2F%287x%5E7-1%29+%29++

such that if you were to substitute u for that expression,
there will be no x's left.

-----------------
Suppose we pick u to be 7x%5E7, then we replace both
the 7x%5E7's by u and get

sqrt%28+%28u%2B1%29%2F%28u-1%29+%29++  

g(x) is simply equal to what we picked u to be, that is,
g(x) = 7x%5E7 

To get f(x) we substitute x for u in

sqrt%28+%28u%2B1%29%2F%28u-1%29+%29++ 

and get 

sqrt%28+%28x%2B1%29%2F%28x-1%29+%29++

So  

f(x) =  sqrt%28+%28x%2B1%29%2F%28x-1%29+%29++
g(x) =  7x%5E7

Checking:

h(x) = fgg(x) = f(g(x)) = f(7x%5E7) =  sqrt%28+%287x%5E7%2B1%29%2F%287x%5E7-1%29+%29++.

Edwin