F(x)=7x+8/x+9; g(x)=9x-8/7-x find f(g(x)) find g(f(x))?

Question

F(x)=7x+8       g(x)=9x-8

        ------               -----

         x+9               7-x

find f(g(x))?

find g(f(x))?

Please show work so I can learn how to solve

Answer 1

Hi Tammie,

 

For the first part wherever there is x in F(x) = 7x-8/x+9 just plug in 9x-8/7-x like this

 

 

[7(9x-8)/(7-x) + 8]/[7 - (9x-8)/(7-x)]

 

The rest is arithmetic. Multiply through - top and bottom of course - by 7-x and collect the like terms

 

I hope this helps