Question

Find the inverse of f(x)=(x−5)/(−4x−2)

Answer 1

Answer:

${f}^{ - 1} (x)= \frac{ 5 - 2x }{ 4x + 1}$

Step-by-step explanation:

The given rational function is

$f(x) = \frac{x - 5}{ - 4x - 2}$

Let

$y = \frac{x - 5}{ - 4x - 2}$

Interchange x and y

$x= \frac{y- 5}{ - 4y - 2}$

Cross multiply

$x( - 4y - 2)= y- 5$

Expand

$- 4xy - 2x= y- 5 \\ - 4xy - y= 2x - 5 \\y( - 4x - 1)= 2x - 5$

Solve for y;

$y= \frac{ 2x - 5}{ - 4x - 1}$

or

$y= \frac{ 5 - 2x }{ 4x + 1}$

Therefore

${f}^{ - 1} (x)= \frac{ 5 - 2x }{ 4x + 1}$