Determine any equations for f^-1 or f inverse

1. f(x) = (-) square root of (x + 1)
2. f(q) = 14q - 2
3. g(t) = (square root of t) + 1
4. f(x) = 6x - x^2, x (is less than or equal to) 3
For # 4 I tried to do it and got:
y=f(x)=6x-x^2=>-y=x^-6x=x^2-6x+9-9=(x-... and so
y+9=(x-3)^2=>x-3=sqrt(y+9)=>x=sqrt(y+9... Hence
x=f^-1(y)=sqrt(y+9)+3.

I was wrong and the answer is actually - y=3- sqrt(9-x). If anyone can help me with 1-3 or walk me through what i did wrong in #4.

Any help is greatly appreciated!!