Find the Inverse f(x)=(x+1)^3

$f (x) = {(x + 1)}^{3}$

Step 1

Write $f (x) = {(x + 1)}^{3}$ as an equation.

$y = {(x + 1)}^{3}$

Step 2

Interchange the variables.

$x = {(y + 1)}^{3}$

Step 3

Solve for $y$ .

Rewrite the equation as ${(y + 1)}^{3} = x$ .

${(y + 1)}^{3} = x$

Take the cube root of both sides of the equation to eliminate the exponent on the left side.

$y + 1 = \sqrt[3]{x}$

Subtract $1$ from both sides of the equation.

$y = \sqrt[3]{x} - 1$

Step 4

Replace $y$ with $f^{- 1} (x)$ to show the final answer.

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

Step 5

Verify if $f^{- 1} (x) = \sqrt[3]{x} - 1$ is the inverse of $f (x) = {(x + 1)}^{3}$ .

To verify the inverse, check if $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ .

Evaluate $f^{- 1} (f (x))$ .

Set up the composite result function.

$f^{- 1} (f (x))$

Evaluate $f^{- 1} ({(x + 1)}^{3})$ by substituting in the value of $f$ into $f^{- 1}$ .

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

Remove parentheses.

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

Pull terms out from under the radical, assuming real numbers.

$f^{- 1} ({(x + 1)}^{3}) = x + 1 - 1$

Combine the opposite terms in $x + 1 - 1$ .

Subtract $1$ from $1$ .

$f^{- 1} ({(x + 1)}^{3}) = x + 0$

Add $x$ and $0$ .

$f^{- 1} ({(x + 1)}^{3}) = x$

Evaluate $f (f^{- 1} (x))$ .

Set up the composite result function.

$f (f^{- 1} (x))$

Evaluate $f (\sqrt[3]{x} - 1)$ by substituting in the value of $f^{- 1}$ into $f$ .

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

Combine the opposite terms in $(\sqrt[3]{x} - 1) + 1$ .

Add $- 1$ and $1$ .

$f (\sqrt[3]{x} - 1) = {(\sqrt[3]{x} + 0)}^{3}$

Add $\sqrt[3]{x}$ and $0$ .

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

Rewrite ${\sqrt[3]{x}}^{3}$ as $x$ .

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt[3]{x}$ as $x^{\frac{1}{3}}$ .

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

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

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

Combine $\frac{1}{3}$ and $3$ .

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

Cancel the common factor of $3$ .

Cancel the common factor.

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

Rewrite the expression.

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

Simplify.

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

Since $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ , then $f^{- 1} (x) = \sqrt[3]{x} - 1$ is the inverse of $f (x) = {(x + 1)}^{3}$ .

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

Find the Inverse f(x)=(x+1)^3

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