Find the Inverse f(x)=(7x+1)/(3x+2)

$f (x) = \frac{7 x + 1}{3 x + 2}$

Step 1

Write $f (x) = \frac{7 x + 1}{3 x + 2}$ as an equation.

$y = \frac{7 x + 1}{3 x + 2}$

Step 2

Interchange the variables.

$x = \frac{7 y + 1}{3 y + 2}$

Step 3

Solve for $y$ .

Rewrite the equation as $\frac{7 y + 1}{3 y + 2} = x$ .

$\frac{7 y + 1}{3 y + 2} = x$

Find the LCD of the terms in the equation.

Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.

$3 y + 2, 1$

Remove parentheses.

$3 y + 2, 1$

The LCM of one and any expression is the expression.

$3 y + 2$

Multiply each term in $\frac{7 y + 1}{3 y + 2} = x$ by $3 y + 2$ to eliminate the fractions.

Multiply each term in $\frac{7 y + 1}{3 y + 2} = x$ by $3 y + 2$ .

$\frac{7 y + 1}{3 y + 2} (3 y + 2) = x (3 y + 2)$

Simplify the left side.

Cancel the common factor of $3 y + 2$ .

Cancel the common factor.

$\frac{7 y + 1}{3 y + 2} (3 y + 2) = x (3 y + 2)$

Rewrite the expression.

$7 y + 1 = x (3 y + 2)$

Simplify the right side.

Apply the distributive property.

$7 y + 1 = x (3 y) + x \cdot 2$

Reorder.

Rewrite using the commutative property of multiplication.

$7 y + 1 = 3 x y + x \cdot 2$

Move $2$ to the left of $x$ .

$7 y + 1 = 3 x y + 2 x$

Solve the equation.

Subtract $3 x y$ from both sides of the equation.

$7 y + 1 - 3 x y = 2 x$

Subtract $1$ from both sides of the equation.

$7 y - 3 x y = 2 x - 1$

Factor $y$ out of $7 y - 3 x y$ .

Factor $y$ out of $7 y$ .

$y \cdot 7 - 3 x y = 2 x - 1$

Factor $y$ out of $- 3 x y$ .

$y \cdot 7 + y (- 3 x) = 2 x - 1$

Factor $y$ out of $y \cdot 7 + y (- 3 x)$ .

$y (7 - 3 x) = 2 x - 1$

Divide each term in $y (7 - 3 x) = 2 x - 1$ by $7 - 3 x$ and simplify.

Divide each term in $y (7 - 3 x) = 2 x - 1$ by $7 - 3 x$ .

$\frac{y (7 - 3 x)}{7 - 3 x} = \frac{2 x}{7 - 3 x} + \frac{- 1}{7 - 3 x}$

Simplify the left side.

Cancel the common factor of $7 - 3 x$ .

Cancel the common factor.

$\frac{y (7 - 3 x)}{7 - 3 x} = \frac{2 x}{7 - 3 x} + \frac{- 1}{7 - 3 x}$

Divide $y$ by $1$ .

$y = \frac{2 x}{7 - 3 x} + \frac{- 1}{7 - 3 x}$

Simplify the right side.

Combine the numerators over the common denominator.

$y = \frac{2 x - 1}{7 - 3 x}$

Step 4

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

$f^{- 1} (x) = \frac{2 x - 1}{7 - 3 x}$

Step 5

Verify if $f^{- 1} (x) = \frac{2 x - 1}{7 - 3 x}$ is the inverse of $f (x) = \frac{7 x + 1}{3 x + 2}$ .

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 $f^{- 1} (\frac{7 x + 1}{3 x + 2})$ by substituting in the value of $f$ into $f^{- 1}$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{2 (\frac{7 x + 1}{3 x + 2}) - 1}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Simplify the numerator.

Combine $2$ and $\frac{7 x + 1}{3 x + 2}$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{2 (7 x + 1)}{3 x + 2} - 1}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{3 x + 2}{3 x + 2}$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{2 (7 x + 1)}{3 x + 2} - 1 \cdot \frac{3 x + 2}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Combine $- 1$ and $\frac{3 x + 2}{3 x + 2}$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{2 (7 x + 1)}{3 x + 2} + \frac{- (3 x + 2)}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Combine the numerators over the common denominator.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{2 (7 x + 1) - (3 x + 2)}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Rewrite $\frac{2 (7 x + 1) - (3 x + 2)}{3 x + 2}$ in a factored form.

Apply the distributive property.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{2 (7 x) + 2 \cdot 1 - (3 x + 2)}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Multiply $7$ by $2$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{14 x + 2 \cdot 1 - (3 x + 2)}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Multiply $2$ by $1$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{14 x + 2 - (3 x + 2)}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Apply the distributive property.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{14 x + 2 - (3 x) - 1 \cdot 2}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Multiply $3$ by $- 1$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{14 x + 2 - 3 x - 1 \cdot 2}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Multiply $- 1$ by $2$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{14 x + 2 - 3 x - 2}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Subtract $3 x$ from $14 x$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x + 2 - 2}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Subtract $2$ from $2$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x + 0}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Add $11 x$ and $0$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{7 - 3 \frac{7 x + 1}{3 x + 2}}$

Simplify the denominator.

Combine $- 3$ and $\frac{7 x + 1}{3 x + 2}$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{7 + \frac{- 3 (7 x + 1)}{3 x + 2}}$

Move the negative in front of the fraction.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{7 - \frac{(3) (7 x + 1)}{3 x + 2}}$

To write $7$ as a fraction with a common denominator, multiply by $\frac{3 x + 2}{3 x + 2}$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{7 (3 x + 2)}{3 x + 2} - \frac{3 (7 x + 1)}{3 x + 2}}$

Combine the numerators over the common denominator.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{7 (3 x + 2) - 3 (7 x + 1)}{3 x + 2}}$

Rewrite $\frac{7 (3 x + 2) - 3 (7 x + 1)}{3 x + 2}$ in a factored form.

Apply the distributive property.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{7 (3 x) + 7 \cdot 2 - 3 (7 x + 1)}{3 x + 2}}$

Multiply $3$ by $7$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{21 x + 7 \cdot 2 - 3 (7 x + 1)}{3 x + 2}}$

Multiply $7$ by $2$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{21 x + 14 - 3 (7 x + 1)}{3 x + 2}}$

Apply the distributive property.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{21 x + 14 - 3 (7 x) - 3 \cdot 1}{3 x + 2}}$

Multiply $7$ by $- 3$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{21 x + 14 - 21 x - 3 \cdot 1}{3 x + 2}}$

Multiply $- 3$ by $1$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{21 x + 14 - 21 x - 3}{3 x + 2}}$

Subtract $21 x$ from $21 x$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{0 + 14 - 3}{3 x + 2}}$

Add $0$ and $14$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{14 - 3}{3 x + 2}}$

Subtract $3$ from $14$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{\frac{11 x}{3 x + 2}}{\frac{11}{3 x + 2}}$

Multiply the numerator by the reciprocal of the denominator.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{11 x}{3 x + 2} \cdot \frac{3 x + 2}{11}$

Cancel the common factor of $11$ .

Factor $11$ out of $11 x$ .

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{11 (x)}{3 x + 2} \cdot \frac{3 x + 2}{11}$

Cancel the common factor.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{11 x}{3 x + 2} \cdot \frac{3 x + 2}{11}$

Rewrite the expression.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{x}{3 x + 2} \cdot (3 x + 2)$

Cancel the common factor of $3 x + 2$ .

Cancel the common factor.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = \frac{x}{3 x + 2} \cdot (3 x + 2)$

Rewrite the expression.

$f^{- 1} (\frac{7 x + 1}{3 x + 2}) = x$

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

Set up the composite result function.

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

Evaluate $f (\frac{2 x - 1}{7 - 3 x})$ by substituting in the value of $f^{- 1}$ into $f$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{7 (\frac{2 x - 1}{7 - 3 x}) + 1}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Simplify the numerator.

Combine $7$ and $\frac{2 x - 1}{7 - 3 x}$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{7 (2 x - 1)}{7 - 3 x} + 1}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Write $1$ as a fraction with a common denominator.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{7 (2 x - 1)}{7 - 3 x} + \frac{7 - 3 x}{7 - 3 x}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Combine the numerators over the common denominator.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{7 (2 x - 1) + 7 - 3 x}{7 - 3 x}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Reorder terms.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{- 3 x + 7 (2 x - 1) + 7}{- 3 x + 7}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Rewrite $\frac{- 3 x + 7 (2 x - 1) + 7}{- 3 x + 7}$ in a factored form.

Apply the distributive property.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{- 3 x + 7 (2 x) + 7 \cdot - 1 + 7}{- 3 x + 7}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Multiply $2$ by $7$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{- 3 x + 14 x + 7 \cdot - 1 + 7}{- 3 x + 7}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Multiply $7$ by $- 1$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{- 3 x + 14 x - 7 + 7}{- 3 x + 7}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Add $- 3 x$ and $14 x$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x - 7 + 7}{- 3 x + 7}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Add $- 7$ and $7$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x + 0}{- 3 x + 7}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Add $11 x$ and $0$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{3 (\frac{2 x - 1}{7 - 3 x}) + 2}$

Simplify the denominator.

Combine $3$ and $\frac{2 x - 1}{7 - 3 x}$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{3 (2 x - 1)}{7 - 3 x} + 2}$

To write $2$ as a fraction with a common denominator, multiply by $\frac{7 - 3 x}{7 - 3 x}$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{3 (2 x - 1)}{7 - 3 x} + \frac{2 (7 - 3 x)}{7 - 3 x}}$

Combine the numerators over the common denominator.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{3 (2 x - 1) + 2 (7 - 3 x)}{7 - 3 x}}$

Reorder terms.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{3 (2 x - 1) + 2 (7 - 3 x)}{- 3 x + 7}}$

Rewrite $\frac{3 (2 x - 1) + 2 (7 - 3 x)}{- 3 x + 7}$ in a factored form.

Apply the distributive property.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{3 (2 x) + 3 \cdot - 1 + 2 (7 - 3 x)}{- 3 x + 7}}$

Multiply $2$ by $3$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{6 x + 3 \cdot - 1 + 2 (7 - 3 x)}{- 3 x + 7}}$

Multiply $3$ by $- 1$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{6 x - 3 + 2 (7 - 3 x)}{- 3 x + 7}}$

Apply the distributive property.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{6 x - 3 + 2 \cdot 7 + 2 (- 3 x)}{- 3 x + 7}}$

Multiply $2$ by $7$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{6 x - 3 + 14 + 2 (- 3 x)}{- 3 x + 7}}$

Multiply $- 3$ by $2$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{6 x - 3 + 14 - 6 x}{- 3 x + 7}}$

Subtract $6 x$ from $6 x$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{0 - 3 + 14}{- 3 x + 7}}$

Subtract $3$ from $0$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{- 3 + 14}{- 3 x + 7}}$

Add $- 3$ and $14$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{\frac{11 x}{- 3 x + 7}}{\frac{11}{- 3 x + 7}}$

Multiply the numerator by the reciprocal of the denominator.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{11 x}{- 3 x + 7} \cdot \frac{- 3 x + 7}{11}$

Cancel the common factor of $11$ .

Factor $11$ out of $11 x$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{11 (x)}{- 3 x + 7} \cdot \frac{- 3 x + 7}{11}$

Cancel the common factor.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{11 x}{- 3 x + 7} \cdot \frac{- 3 x + 7}{11}$

Rewrite the expression.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{x}{- 3 x + 7} \cdot (- 3 x + 7)$

Multiply $\frac{x}{- 3 x + 7}$ by $- 3 x + 7$ .

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{x (- 3 x + 7)}{- 3 x + 7}$

Cancel the common factor of $- 3 x + 7$ .

Cancel the common factor.

$f (\frac{2 x - 1}{7 - 3 x}) = \frac{x (- 3 x + 7)}{- 3 x + 7}$

Divide $x$ by $1$ .

$f (\frac{2 x - 1}{7 - 3 x}) = x$

Since $f^{- 1} (f (x)) = x$ and $f (f^{- 1} (x)) = x$ , then $f^{- 1} (x) = \frac{2 x - 1}{7 - 3 x}$ is the inverse of $f (x) = \frac{7 x + 1}{3 x + 2}$ .

$f^{- 1} (x) = \frac{2 x - 1}{7 - 3 x}$

Find the Inverse f(x)=(7x+1)/(3x+2)

Related Questions

Support LCMGCF.com by disabling your adblocker.