Let `f(x) = 9+\sqrt(x-4) `. Find ` f^(-1)(x) `.

 ` f^(-1)(x) = `   .

The restricted domain of `f^-1(x)` is  

Box 1: Enter your answer as an expression. Example: 3x^2+1, x/5, (a+b)/c
Be sure your variables match those in the question

Box 2: Enter your answer using interval notation. Example: [2,5)
Use U for union to combine intervals. Example: (-oo,2] U [4,oo)
Enter each value as a number (like 5, -3, 2.2172) or as a calculation (like 5/3, 2^3, 5+4)
Enter DNE for an empty set. Use oo to enter Infinity.