Question

LAST QUESTION GUYS PLEASE LORD HELP ME

Answer 1

ANSWER

D. 13

EXPLANATION

The given function is:

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

Let

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

Interchange x and y.

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

Solve for y.

$x(y - 4)=2y + 1$

$xy - 4x=2y + 1$

$xy - 2y = 1 + 4x$

$(x - 2)y = 1 + 4x$

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

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

We put x=3,

${f}^{ - 1}(3) = \frac{1 + 4 \times 3}{3- 2}$

${f}^{ - 1}(3) = \frac{13}{1} = 13$