Math Problem Statement

Evaluate each of the following expressions given the function definitions for f, g, and h. f ( x )

√ x + 5

g ( x )

4 x − 8

h ( x )

7 x

f ( g ( 5 ) )

g ( f ( 87 ) )

h ( g ( f ( 2 ) ) )

Solution

Let's evaluate each expression step-by-step.

Given Function Definitions:

  1. f(x)=x+5f(x) = \sqrt{x} + 5
  2. g(x)=4x8g(x) = 4x - 8
  3. h(x)=7xh(x) = 7x

Now, let's evaluate each expression in sequence.


Expression 1: f(g(5))f(g(5))

  1. Evaluate g(5)g(5): g(5)=4(5)8=208=12g(5) = 4(5) - 8 = 20 - 8 = 12

  2. Substitute into f(x)f(x): f(g(5))=f(12)=12+5f(g(5)) = f(12) = \sqrt{12} + 5

    Simplify: f(12)=12+53.464+5=8.464f(12) = \sqrt{12} + 5 \approx 3.464 + 5 = 8.464

So, f(g(5))8.464f(g(5)) \approx 8.464.


Expression 2: g(f(87))g(f(87))

  1. Evaluate f(87)f(87): f(87)=87+5f(87) = \sqrt{87} + 5

    Approximate 87\sqrt{87}: f(87)9.327+5=14.327f(87) \approx 9.327 + 5 = 14.327

  2. Substitute into g(x)g(x): g(f(87))=g(14.327)=4(14.327)8g(f(87)) = g(14.327) = 4(14.327) - 8

    Multiply and simplify: g(14.327)57.3088=49.308g(14.327) \approx 57.308 - 8 = 49.308

So, g(f(87))49.308g(f(87)) \approx 49.308.


Expression 3: h(g(f(2)))h(g(f(2)))

  1. Evaluate f(2)f(2): f(2)=2+5f(2) = \sqrt{2} + 5

    Approximate 2\sqrt{2}: f(2)1.414+5=6.414f(2) \approx 1.414 + 5 = 6.414

  2. Substitute into g(x)g(x): g(f(2))=g(6.414)=4(6.414)8g(f(2)) = g(6.414) = 4(6.414) - 8

    Multiply and simplify: g(6.414)25.6568=17.656g(6.414) \approx 25.656 - 8 = 17.656

  3. Substitute into h(x)h(x): h(g(f(2)))=h(17.656)=7(17.656)h(g(f(2))) = h(17.656) = 7(17.656)

    Multiply: h(17.656)123.592h(17.656) \approx 123.592

So, h(g(f(2)))123.592h(g(f(2))) \approx 123.592.


Final Answers:

  1. f(g(5))8.464f(g(5)) \approx 8.464
  2. g(f(87))49.308g(f(87)) \approx 49.308
  3. h(g(f(2)))123.592h(g(f(2))) \approx 123.592

Would you like further details on any step?


Here are five related questions to extend your understanding:

  1. What happens if we replace f(x)f(x) with f(x)=x2+5f(x) = x^2 + 5 and re-evaluate these expressions?
  2. How would the answers change if we used g(x)=x38g(x) = x^3 - 8 instead?
  3. If h(x)=2x+3h(x) = 2x + 3, what would be the result of h(g(f(5)))h(g(f(5)))?
  4. Can we find f(g(x))f(g(x)) as a function of xx instead of specific values?
  5. How can these compositions of functions be visualized graphically?

Tip: When working with function compositions, breaking down each step carefully helps prevent errors and simplifies complex expressions.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Algebra
Square Roots
Linear Functions

Formulas

f(x) = √x + 5
g(x) = 4x - 8
h(x) = 7x
Composition of functions: (f ∘ g)(x) = f(g(x))

Theorems

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Suitable Grade Level

Grades 9-11