f(x)=(x+12)/(x-4) if f(x) = 1 find X

f(x) = 1 = (x+12)/(x-4)     Multiply both sides by x-4

(1) (x-4) = x + 12             Add 4 to both sides

x = x + 16                        Subtract xfrom both sides

0 = 16       ERROR......  NOT TRUE.....This has no solution !

Thanks, EP.....Here's another way to see this :

If

1  = ( x + 12) / (x - 4)....then the numerator and denominator would have to be the same thing because   a / a  = 1    [ and a ≠ 0 ]