Question 28857
f(x) = 5x-9


--> y = 5x-9
y+9 = 5x
--> {{{ x = (y+9)/5 }}}


so, the inverse function is {{{ f^(-1)(x) = (x+9)/5 }}}



Verify...

pick any value of x and put it into f(x) to get a value of f(x).


f(1) = 5(1)-9
f(1) = 5-9
f(1) = -4


So, now put -4 into the inverse function and the answer we expect is 1.


{{{ f^(-1)(-4) = (-4+9)/5 }}}
{{{ f^(-1)(-4) = 5/5 }}}
{{{ f^(-1)(-4) = 1 }}}


jon.