What is the equation of the inverse of ?

Question

What is the equation of the inverse of g(x)=2/5x-1 ?

 

A.g^-1(x)=5/2(x+1)

B.g^-1(x)=2/5(x-1)

C.g^-1(x)=-2/5+1

D.g^-1(x)=5/2-1

 

 

Answer 1

To find the inverse function:

 

1. Change the function name y:

 

y = 2/5 x -1

 

2. Switch x and y:

 

x = 2/5 y -1

 

3. Solve for y:

 

x = 2/5 y -1

x + 1 = 2/5 y

5/2 (x + 1) = y

 

That gives you the inverse functions, so A is correct

 

 

 

Answer 2

A is the correct answer.  

To find an inverse, your first step is to set your function equal to Y.  Then solve for x (get the x all by itself).  Once this is done, switch the x and y values, and you have the inverse.

1.  y = 2/5x - 1

2.  y + 1 = 2/5x

    5/2(y + 1) = x

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

    5/2(x + 1) = f'(x)