444,910 views
13 votes
13 votes
Find the function that corresponds to this inverse functionf(x)=3x+1/-5x-2, x ≠ -2/5

User Hebert
by
2.4k points

1 Answer

14 votes
14 votes

Answer::


f^(-1)(x)=-(1+2x)/(3+5x),x\cancel{=}-(3)/(5)

Explanation:

We want to find the function that corresponds to the inverse function:


f(x)=(3x+1)/(-5x-2),x\cancel{=}-(2)/(5)

To do this, we find the inverse of f(x).

In order to find the inverse of f(x), follow the steps below:

Step 1: Replace f(x) with y:


y=(3x+1)/(-5x-2)

Step 2: Swap x and y


x=(3y+1)/(-5y-2)

Step 3: Make y the subject of the equation:


\begin{gathered} \text{ Cross multiply} \\ x(-5y-2)=3y+1 \\ \text{ Open the bracket on the left side:} \\ -5xy-2x=3y+1 \\ \text{ Bring all the terms containing y to one side of the equation.} \\ -5xy-3y=1+2x \\ \text{ Factor out y} \\ y(-5x-3)=1+2x \\ \text{ Divide both sides by }-5x-3 \\ y=(1+2x)/(-5x-3) \end{gathered}

Step 4: Replace y the inverse of f(x).


f^(-1)(x)=(1+2x)/(-5x-3)=(1+2x)/(-(5x+3))=-(1+2x)/(3+5x)

The function that corresponds to the given inverse function is:


f^(-1)(x)=-(1+2x)/(3+5x),x\cancel{=}-(3)/(5)

User HiFI
by
2.6k points