Question

3 over the whole value of (x2−5x+6) = a over the whole value of (x−2) + b over the whole value of (x−3)

Answer 1

I guess that's all you can do
to find a and b you need more information

b=-a -> a (x-3)-a (x-2)=3
a [x-3-(x-2)]=3
a (x-3-x+2)=3
a*(-1)=3
a=3:(-1)
a=-3
b=-a=-(-3)=3