Math Problem Statement

Find the inverse function of f(x) for the given functions: (a) f(x) = x^2 + 3x - 1, x > -3/2; (b) f(x) = -4x + 8; (c) f(x) = x^3 - 2; (d) f(x) = e^x; (e) f(x) = sqrt(x + 1); (f) f(x) = ln(x + 2).

Solution

Let's work through the inverses of the given functions.

(a) f(x)=x2+3x1f(x) = x^2 + 3x - 1, x>32x > -\frac{3}{2}

To find the inverse:

  1. Set y=x2+3x1y = x^2 + 3x - 1.
  2. Swap xx and yy and solve for yy: x=y2+3y1x = y^2 + 3y - 1 This quadratic equation in yy is tricky to solve directly, but it's a standard method. We can use the quadratic formula: y=3±324(1)(1+x)2y = \frac{-3 \pm \sqrt{3^2 - 4(1)(-1+x)}}{2} Solving this would yield the inverse, which is quite complex.

(b) f(x)=4x+8f(x) = -4x + 8

  1. Set y=4x+8y = -4x + 8.
  2. Swap xx and yy: x=4y+8x = -4y + 8
  3. Solve for yy: y=8x4y = \frac{8 - x}{4} Thus, the inverse function is: f1(x)=8x4f^{-1}(x) = \frac{8 - x}{4}

(c) f(x)=x32f(x) = x^3 - 2

  1. Set y=x32y = x^3 - 2.
  2. Swap xx and yy: x=y32x = y^3 - 2
  3. Solve for yy: y=x+23y = \sqrt[3]{x + 2} Thus, the inverse function is: f1(x)=x+23f^{-1}(x) = \sqrt[3]{x + 2}

(d) f(x)=exf(x) = e^x

  1. Set y=exy = e^x.
  2. Swap xx and yy: x=eyx = e^y
  3. Solve for yy by taking the natural logarithm on both sides: y=ln(x)y = \ln(x) Thus, the inverse function is: f1(x)=ln(x)f^{-1}(x) = \ln(x)

(e) f(x)=x+1f(x) = \sqrt{x + 1}

  1. Set y=x+1y = \sqrt{x + 1}.
  2. Swap xx and yy: x=y+1x = \sqrt{y + 1}
  3. Square both sides to solve for yy: x2=y+1y=x21x^2 = y + 1 \quad \Rightarrow \quad y = x^2 - 1 Thus, the inverse function is: f1(x)=x21f^{-1}(x) = x^2 - 1

(f) f(x)=ln(x+2)f(x) = \ln(x + 2)

  1. Set y=ln(x+2)y = \ln(x + 2).
  2. Swap xx and yy: x=ln(y+2)x = \ln(y + 2)
  3. Exponentiate both sides to get rid of the logarithm: ex=y+2y=ex2e^x = y + 2 \quad \Rightarrow \quad y = e^x - 2 Thus, the inverse function is: f1(x)=ex2f^{-1}(x) = e^x - 2

Would you like more details on any of these steps?

Relative Questions:

  1. How can we determine if a function has an inverse?
  2. What are the necessary conditions for a function to have an inverse?
  3. How does the domain of a function affect its inverse?
  4. Can all quadratic functions have inverses?
  5. How do you verify if two functions are inverses of each other?

Tip:

Always check the domain and range of both the function and its inverse, as they often provide important constraints, especially for square roots or logarithms.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Algebra
Quadratic Equations
Exponential and Logarithmic Functions

Formulas

Quadratic formula: y = (-b ± sqrt(b^2 - 4ac)) / 2a
Cubic root: y = (x + 2)^(1/3)
Natural logarithm inverse: y = ln(x)
Square both sides to remove square roots
Exponentiation to solve logarithmic equations

Theorems

Inverse Function Theorem
One-to-One Functions and Invertibility

Suitable Grade Level

High School (Grades 10-12) or College Precalculus