here, equation is like this. E = B - (X2 / AT)
here E is made OF difference of two terms B and (X2/AT)
THEREFORE
Dimension of B is the same as E i.e.[ M1 L2 T-2] Energy = Force x Distance = Mass x Acceleration x Distance
Also, dimension of (X2/AT) is the same as E i.e. [ M1 L2 T-2]
Now, X=distance = [ m0 L1 t0 ]
& T=time = [m0 lo T1]
therefore dimension of A is found as below.
Dim.of (X2/AT) = {Dim.of X2} / {Dim. of A } x {Dim. of T}
so {M1 L2 T-2} = {M0 L2 T0} / { Ma Lb Tc } x { M0 L0 T1}
so {M1 L2 T-2} = {M0 L2 T-1} / {Ma Lb Tc}
so {M1 L2 T-2} = { M0-a L2-b T-1-c }
COMPARING
0-a = 1 so a = -1
2-b = 2 so b = 0
-1-c =-2 so c = 1
Therefore Dimensions of A is [ Ma Lb Tc ] = [ M-1 L0 T1 ] i.e. unit is s/kg.
We knew that Dimension of B is same as Energy i.e.[ M1 L2 T-2]
i.e. unit is kg-m2/s2 i.e. kg-m/s2 * m i.e.N-m i.e. Joule
THUS
Dimensions of A*B is
[ M-1 L0 T1] * [M1 L2 T-2] = [M0 L2 T-1] i.e. unit is m2/s which is the unit of Kinematic Viscosity.
hope u got it