Question

Which pair of functions is not a pair of inverse functions?

A.f(x)=x+1/6 and g(x)=6x-1
B.f(x)= x-4/19 and g(x)=19x+4
C.f(x)=x5 and g(x)=x divided by 5
D.f(x)=x/x+20 and g(x)=20x/x-1

Answer 1

d

I would do the math out. but I'm lazy. message me if you want me to

Answer 2

option D

Explanation:

To find inverse , we replace f(x) by y. then swap the variables x and y. finally solve the equation for y

(a) y=(x+1)/6

x= (y+1)/6

6x= y+1

y=6x-1 that is our g(x)

(b) y=(x-4)/19

x= (y-4)/19

19x=y-4

y=19x+4 that is our g(x)

(c) y=5x

x=5y

y= x/5 that is our g(x)

(d) y=x/(x+20)

`x=(y)/(y+20)`

cross multiply

x(y+20)= y

xy+20x= y

subtract xy on both sides

20x= y-xy

20x= y(1-x)

so y= 20x/(1-x) that is not our g(x)