Math Problem Statement

Given a series of problems involving composite and inverse functions, solve each question accordingly.

Solution

Let's go through each question one by one and solve them.

  1. Given f(x)=8x+5f(x) = 8x + 5 and g(x)=x+2g(x) = x + 2, if (fg)(x)=37(f \circ g)(x) = 37, find xx.

    • Start by calculating f(g(x))f(g(x)): f(g(x))=f(x+2)=8(x+2)+5=8x+16+5=8x+21f(g(x)) = f(x + 2) = 8(x + 2) + 5 = 8x + 16 + 5 = 8x + 21
    • Set 8x+21=378x + 21 = 37 and solve for xx: 8x=16x=28x = 16 \Rightarrow x = 2
  2. Given g(x)=x3g(x) = x - 3 and (gf)(x)=2x2(g \circ f)(x) = 2x - 2, find f(x)f(x).

    • Start by expressing (gf)(x)=g(f(x))(g \circ f)(x) = g(f(x)): g(f(x))=f(x)3g(f(x)) = f(x) - 3
    • Since (gf)(x)=2x2(g \circ f)(x) = 2x - 2, set up the equation: f(x)3=2x2f(x) - 3 = 2x - 2
    • Solve for f(x)f(x): f(x)=2x+1f(x) = 2x + 1
  3. If f(x)=x+4f(x) = x + 4, g(x)=x2+1g(x) = x^2 + 1, and h(x)=3xh(x) = 3x, find (hgf)(x)(h \circ g \circ f)(x).

    • First, calculate g(f(x))g(f(x)): f(x)=x+4g(f(x))=(x+4)2+1=x2+8x+16+1=x2+8x+17f(x) = x + 4 \Rightarrow g(f(x)) = (x + 4)^2 + 1 = x^2 + 8x + 16 + 1 = x^2 + 8x + 17
    • Now calculate h(g(f(x)))h(g(f(x))): h(g(f(x)))=h(x2+8x+17)=3(x2+8x+17)=3x2+24x+51h(g(f(x))) = h(x^2 + 8x + 17) = 3(x^2 + 8x + 17) = 3x^2 + 24x + 51
  4. If f(x)=3x14x2f(x) = \frac{3x - 1}{4x - 2}, find f1(0)f^{-1}(0).

    • Set f(x)=0f(x) = 0: 3x14x2=0\frac{3x - 1}{4x - 2} = 0
    • Solve for xx when the numerator is zero: 3x1=0x=133x - 1 = 0 \Rightarrow x = \frac{1}{3}
    • Therefore, f1(0)=13f^{-1}(0) = \frac{1}{3}.
  5. Given f(x)=x4f(x) = x - 4 and g(x)=3x+2g(x) = 3x + 2, find (fg)1(x)(f \circ g)^{-1}(x).

    • First, calculate (fg)(x)(f \circ g)(x): f(g(x))=f(3x+2)=3x+24=3x2f(g(x)) = f(3x + 2) = 3x + 2 - 4 = 3x - 2
    • Now, to find (fg)1(x)(f \circ g)^{-1}(x), set y=3x2y = 3x - 2 and solve for xx: y+2=3xx=y+23y + 2 = 3x \Rightarrow x = \frac{y + 2}{3}
    • So, (fg)1(x)=x+23(f \circ g)^{-1}(x) = \frac{x + 2}{3}.

Would you like further explanations or details on any of these steps?

Here are some questions to deepen your understanding:

  1. What would happen if f(x)f(x) and g(x)g(x) were switched in Question 1?
  2. How do you find the inverse of a function in general?
  3. What is the significance of function composition in mathematics?
  4. How can we verify that our answer to an inverse function is correct?
  5. What are some practical applications of function composition?

Tip: When dealing with composite functions, always work step-by-step from the innermost function to the outermost for clarity and accuracy.

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Math Problem Analysis

Mathematical Concepts

Composite Functions
Inverse Functions
Function Operations

Formulas

Composite function: (f ∘ g)(x) = f(g(x))
Inverse function f⁻¹(x) satisfies f(f⁻¹(x)) = x
Solving equations to find specific values of x in composite functions

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 10-12