Answer:

Take F(x) = 0

x^2-4x+3 = 0

or, x^2 -3x-x+3 = 0

or, x(x-3)-1(x-3)=0

or, (x-3)(x-1)= 0

or, (x-3) =0

or, x= 3

or, (x-1) = 0

or, x= 1

so, a=3 , B=1

3a = 3×3 = 9

3B = 3×1 = 3