Find the Inverse f(x)=(x+9)^(1/2)

$f (x) = {(x + 9)}^{\frac{1}{2}}$

Step 1

Write $f (x) = {(x + 9)}^{\frac{1}{2}}$ as an equation.

$y = {(x + 9)}^{\frac{1}{2}}$

Step 2

Interchange the variables.

$x = {(y + 9)}^{\frac{1}{2}}$

Step 3

Solve for $y$ .

Rewrite the equation as ${(y + 9)}^{\frac{1}{2}} = x$ .

${(y + 9)}^{\frac{1}{2}} = x$

Raise each side of the equation to the power of $2$ to eliminate the fractional exponent on the left side.

${({(y + 9)}^{\frac{1}{2}})}^{2} = x^{2}$

Simplify the left side.

Simplify ${({(y + 9)}^{\frac{1}{2}})}^{2}$ .

Multiply the exponents in ${({(y + 9)}^{\frac{1}{2}})}^{2}$ .

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

${(y + 9)}^{\frac{1}{2} \cdot 2} = x^{2}$

Cancel the common factor of $2$ .

Cancel the common factor.

${(y + 9)}^{\frac{1}{2} \cdot 2} = x^{2}$

Rewrite the expression.

${(y + 9)}^{1} = x^{2}$

Simplify.

$y + 9 = x^{2}$

Subtract $9$ from both sides of the equation.

$y = x^{2} - 9$

Step 4

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

$f^{- 1} (x) = x^{2} - 9$

Step 5

Verify if $f^{- 1} (x) = x^{2} - 9$ is the inverse of $f (x) = {(x + 9)}^{\frac{1}{2}}$ .

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 $f^{- 1} ({(x + 9)}^{\frac{1}{2}})$ by substituting in the value of $f$ into $f^{- 1}$ .

$f^{- 1} ({(x + 9)}^{\frac{1}{2}}) = {({(x + 9)}^{\frac{1}{2}})}^{2} - 9$

Simplify each term.

Multiply the exponents in ${({(x + 9)}^{\frac{1}{2}})}^{2}$ .

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

$f^{- 1} ({(x + 9)}^{\frac{1}{2}}) = {(x + 9)}^{\frac{1}{2} \cdot 2} - 9$

Cancel the common factor of $2$ .

Cancel the common factor.

$f^{- 1} ({(x + 9)}^{\frac{1}{2}}) = {(x + 9)}^{\frac{1}{2} \cdot 2} - 9$

Rewrite the expression.

$f^{- 1} ({(x + 9)}^{\frac{1}{2}}) = (x + 9) - 9$

Simplify.

$f^{- 1} ({(x + 9)}^{\frac{1}{2}}) = x + 9 - 9$

Combine the opposite terms in $x + 9 - 9$ .

Subtract $9$ from $9$ .

$f^{- 1} ({(x + 9)}^{\frac{1}{2}}) = x + 0$

Add $x$ and $0$ .

$f^{- 1} ({(x + 9)}^{\frac{1}{2}}) = x$

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

Set up the composite result function.

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

Evaluate $f (x^{2} - 9)$ by substituting in the value of $f^{- 1}$ into $f$ .

$f (x^{2} - 9) = {((x^{2} - 9) + 9)}^{\frac{1}{2}}$

Combine the opposite terms in $(x^{2} - 9) + 9$ .

Add $- 9$ and $9$ .

$f (x^{2} - 9) = {(x^{2} + 0)}^{\frac{1}{2}}$

Add $x^{2}$ and $0$ .

$f (x^{2} - 9) = {(x^{2})}^{\frac{1}{2}}$

Multiply the exponents in ${(x^{2})}^{\frac{1}{2}}$ .

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

$f (x^{2} - 9) = x^{2 (\frac{1}{2})}$

Cancel the common factor of $2$ .

Cancel the common factor.

$f (x^{2} - 9) = x^{2 (\frac{1}{2})}$

Rewrite the expression.

$f (x^{2} - 9) = x$

Since $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ , then $f^{- 1} (x) = x^{2} - 9$ is the inverse of $f (x) = {(x + 9)}^{\frac{1}{2}}$ .

$f^{- 1} (x) = x^{2} - 9$

Find the Inverse f(x)=(x+9)^(1/2)

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