1. The problem statement, all variables and given/known data For exercises 49 and 50 let f(x) = (ax + b)/(cx + d) 50. Determine the constants a, b, c, d for which f = f-1 2. Relevant equations I found in question 49 when they asked to find f-1 that: f-1 = (dx - b)/(a - cx) This was also the answer at the back of the book but you are free to double check. 3. The attempt at a solution I made f(x) = f-1(x) (ax + b)/(cx + d) = (dx - b)/(a - cx) a2x - acx2 + ab - bcx = d2x - bcx - bd From this i realized that finding the values for b and c would be manageable: For b: ab + bd = cdx2 + d2x + acx2 - a2x b ( a + d) = cdx2 + d2x + acx2 - a2x b = (cdx2 + d2x+ acx2 - a2x) / (a + d) For c: -acx - cdx2 = d2x - bd - a2x -ab c (-ax - dx2) = d2x - bd - a2x -ab c = (d2x - bd - a2x -ab)/(-ax - dx2) However i do not know how to find the constants a and d because you cannot just factor them out without leaving them in. Please help, Thank you.