Math Problem Statement

29. Suppose H(x) = (√(1 + √x))/(√(2 + √x)) and g(x) = √x. (a) Find a function f such that h = f ∘ g. (b) Find a function f such that h = g ∘ f. 47. The exact number of yards in c centimeters is f(c), where f is the function defined by f(c) = c / 91.44. (a) Find a formula for f⁻¹(y). (b) What is the meaning of f⁻¹(y)?

Solution

Let's tackle both problems from your image step by step.

Problem 29:

We are given: H(x)=1+x2+xH(x) = \frac{\sqrt{1 + \sqrt{x}}}{\sqrt{2 + \sqrt{x}}} and g(x)=x.g(x) = \sqrt{x}.

(a) Find a function ff such that h=fgh = f \circ g.

We want to express H(x)H(x) in the form of f(g(x))f(g(x)), meaning we need to find an f(x)f(x) such that: H(x)=f(g(x))=f(x).H(x) = f(g(x)) = f(\sqrt{x}). By inspection, comparing H(x)H(x) and g(x)g(x), we see that H(x)H(x) involves nested square roots. If we substitute g(x)=xg(x) = \sqrt{x} directly into H(x)H(x), we need to match it to: f(x)=1+x2+x.f(\sqrt{x}) = \frac{\sqrt{1 + \sqrt{x}}}{\sqrt{2 + \sqrt{x}}}. Thus, the function f(x)f(x) that we need would simply be: f(x)=1+x2+x.f(x) = \frac{\sqrt{1 + x}}{\sqrt{2 + x}}.

(b) Find a function ff such that h=gfh = g \circ f.

Now we need to find an f(x)f(x) such that h(x)=g(f(x))=f(x)h(x) = g(f(x)) = \sqrt{f(x)}.

Since H(x)H(x) is expressed as: H(x)=1+x2+x,H(x) = \frac{\sqrt{1 + \sqrt{x}}}{\sqrt{2 + \sqrt{x}}}, we need f(x)f(x) to satisfy: f(x)=1+x2+x.\sqrt{f(x)} = \frac{\sqrt{1 + \sqrt{x}}}{\sqrt{2 + \sqrt{x}}}. To solve for f(x)f(x), square both sides: f(x)=(1+x2+x)2=1+x2+x.f(x) = \left( \frac{\sqrt{1 + \sqrt{x}}}{\sqrt{2 + \sqrt{x}}} \right)^2 = \frac{1 + \sqrt{x}}{2 + \sqrt{x}}.

So, the function f(x)f(x) is: f(x)=1+x2+x.f(x) = \frac{1 + \sqrt{x}}{2 + \sqrt{x}}.


Problem 47:

We are given: f(c)=c91.44f(c) = \frac{c}{91.44} where f(c)f(c) gives the exact number of yards in cc centimeters.

(a) Find a formula for f1(y)f^{-1}(y).

To find the inverse of f(c)f(c), we need to solve for cc in terms of yy (the number of yards). Start with: y=c91.44.y = \frac{c}{91.44}. Multiply both sides by 91.44 to solve for cc: c=91.44y.c = 91.44y. Thus, the inverse function is: f1(y)=91.44y.f^{-1}(y) = 91.44y.

(b) What is the meaning of f1(y)f^{-1}(y)?

The function f1(y)f^{-1}(y) gives the number of centimeters corresponding to yy yards. In other words, if you know the number of yards yy, f1(y)f^{-1}(y) converts that value back into centimeters.


Would you like any further details or explanations?

Here are some follow-up questions:

  1. How do you generally find the inverse of a function?
  2. Why does the function composition involve substitution?
  3. Can all functions be composed in this way (like in 29(a) and 29(b))?
  4. Why is squaring necessary in part 29(b)?
  5. How do unit conversions relate to function inverses, as in problem 47?

Tip: When finding the inverse of a function, always check if the inverse is valid by substituting it back into the original function to see if you retrieve the identity function (i.e., f(f1(x))=xf(f^{-1}(x)) = x).

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Math Problem Analysis

Mathematical Concepts

Function Composition
Inverse Functions
Algebraic Manipulation
Square Roots
Unit Conversion

Formulas

H(x) = (√(1 + √x))/(√(2 + √x))
g(x) = √x
f⁻¹(y) = 91.44y

Theorems

Function Composition
Inverse Function Theorem

Suitable Grade Level

Grades 11-12