Inverse of y=9-x²; you just replace x by y and y by x: x=9-y².
And the value of y: y² = 9-x and y =√(9 - x) [this is the inverse function]
f⁻¹(x) = √(9-x): CONDITION : (9-x) >=0, that means x< or = 9
Answer as per your problem:
The inverse of the function y = 9 - x 2, for all values x ≥ 3, is _____y =√(9 - x), where x can take values _____x<=9.