By the principle of dimensional homogeneity, quantities added or subtracted must have the same dimensions. In the denominator, B is added to x (distance).
[B]=[x]=[L]
The dimensions of potential energy V are [M1L2T−2].
From the given equation V=x+BAx, we can write the dimensional formula as:
[V]=[x+B][A][x]1/2
[M1L2T−2]=[L][A][L]1/2
[M1L2T−2]=[A][L]−1/2
[A]=[M1L2T−2][L]1/2=[M1L5/2T−2]
Now, the dimensions of AB are:
[AB]=[A][B]=[M1L5/2T−2][L]=[M1L7/2T−2]
Answer: [M1L7/2T−2]