Math Problem Statement

let f(x) = cube root of x, solve each of the ff equations for x

(f(x))^-1 = 11, then x = f^-1(x) = 11, then x = f(x^-1) = 11, then x =

Solution

Let's solve each equation step by step, given f(x)=x3f(x) = \sqrt[3]{x}.

1. (f(x))1=11(f(x))^{-1} = 11

We know that f(x)=x3f(x) = \sqrt[3]{x}, so:

(f(x))1=1f(x)=11(f(x))^{-1} = \frac{1}{f(x)} = 11

This implies:

1x3=11\frac{1}{\sqrt[3]{x}} = 11

Now, solve for xx:

x3=111\sqrt[3]{x} = \frac{1}{11}

Cube both sides:

x=(111)3=1113=11331x = \left(\frac{1}{11}\right)^3 = \frac{1}{11^3} = \frac{1}{1331}

Thus, x=11331x = \frac{1}{1331}.


2. f1(x)=11f^{-1}(x) = 11

f1(x)f^{-1}(x) represents the inverse of f(x)f(x), where f(x)=x3f(x) = \sqrt[3]{x}. The inverse of f(x)f(x) is f1(x)=x3f^{-1}(x) = x^3.

Given:

f1(x)=11f^{-1}(x) = 11

This means:

x3=11x^3 = 11

Solve for xx:

x=113x = \sqrt[3]{11}

So, x=113x = \sqrt[3]{11} (or approximately x2.223x \approx 2.223).


3. f(x1)=11f(x^{-1}) = 11

We know f(x)=x3f(x) = \sqrt[3]{x}, so:

[ f(x^{-1}) = \sqrt[3]{x^{-1}} = \frac{1}{\sqrt[3]{x}} ]

Given:

1x3=11\frac{1}{\sqrt[3]{x}} = 11

This is the same as the first equation:

x3=111\sqrt[3]{x} = \frac{1}{11}

Cube both sides:

x=1113=11331x = \frac{1}{11^3} = \frac{1}{1331}

Thus, x=11331x = \frac{1}{1331}.


Summary of Solutions:

  1. (f(x))1=11x=11331(f(x))^{-1} = 11 \Rightarrow x = \frac{1}{1331}
  2. f1(x)=11x=113f^{-1}(x) = 11 \Rightarrow x = \sqrt[3]{11}
  3. f(x1)=11x=11331f(x^{-1}) = 11 \Rightarrow x = \frac{1}{1331}

Would you like more details or explanations?

Here are 5 related questions to expand on this:

  1. How do you calculate the inverse of a function?
  2. What are the properties of cube roots in solving equations?
  3. How do you solve equations with exponents in the denominator?
  4. What is the significance of a function’s inverse in algebra?
  5. How do you interpret and solve f(x1)f(x^{-1})?

Tip: Always check whether you need to take the inverse of the function or the inverse of the variable before solving.

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Math Problem Analysis

Mathematical Concepts

Algebra
Inverse Functions
Cube Roots

Formulas

f(x) = cube root of x
(f(x))^-1 = 1/f(x)
f^-1(x) = x^3

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 10-12